Photocatalytic fuel cell (PFC) is considered as a sustainable green technology which could degrade organic pollutant and generate electricity simultaneously. A synergistic double-sided ZnO/BaTiO3 loaded carbon plate heterojunction photoanode was fabricated in different ratios by using simple ultrasonication and mixed-annealed method. The double-sided design of photoanode allowed the lights irradiated at both sides of the photoanode. The ferroelectricity fabricated photoanode was applied in a membraneless PFC with platinum-loaded carbon as the cathode. Results revealed that the photoanode with 1:1 ratio of BaTiO3 and ZnO exhibited a superior photocatalytic activity among all the photoanodes prepared in this study. The heterojunction of this photoanode was able to achieve up to a removal efficiency of 93.67% with a maximum power density of 0.5284 μW cm-2 in 10 mg L-1 of Reactive Red 120 (RR120) without any supporting electrolyte. This photoanode was able to maintain at high performance after recycling 3 times. Overloading of ZnO above 50% on BaTiO3 could lead to deterioration of the performance of PFC due to the charge defects and light trapping ability. The interactions, interesting polarizations of the photocatalysts and proposed mechanism of the n-n type heterojunction in the photoanode of ZnO/BaTiO3 was also discussed.
This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) and assess the risk to health at different sites in Malaysia. Continuous monitoring of BTEX in Kuala Lumpur City Centre, Kuala Terengganu, Kota Kinabalu and Fraser Hill were conducted using Online Gas Chromatograph. For comparison, BTEX at selected hotspot locations were determined by active sampling method using sorbent tubes and Thermal Desorption Gas Chromatography Mass Spectrometry. The hazard quotient (HQ) for non-carcinogenic and the life-time cancer risk (LTCR) of BTEX were calculated using the United States Environmental Protection Agency (USEPA) health risk assessment (HRA) methods. The results showed that the highest total BTEX concentrations using continuous monitoring were recorded in the Kuala Lumpur City Centre (49.56 ± 23.71 μg/m3). Toluene was the most dominant among the BTEX compounds. The average concentrations of benzene ranged from 0.69 ± 0.45 μg/m3 to 6.20 ± 3.51 μg/m3. Measurements using active sampling showed that BTEX concentrations dominated at the roadside (193.11 ± 114.57 μg/m3) in comparison to petrol station (73.08 ± 30.41 μg/m3), petrochemical industry (32.10 ± 13.13 μg/m3) and airport (25.30 ± 6.17 μg/m3). Strong correlations among BTEX compounds (p<0.01, r>0.7) at Kuala Lumpur City Centre showed that BTEX compounds originated from similar sources. The values of HQ at all stations were <1 indicating the non-carcinogenic risk are negligible and do not pose threats to human health. The LTCR value based on benzene inhalation (1.59 × 10-5) at Kuala Lumpur City Centre were between 1 × 10-4 and 1 × 10-5, representing a probable carcinogenic risk.
This work studied the potential of using eggshell (ES) (200-300 μm) waste as adsorbent for sequential removal of heavy metals, soluble microbial products, and dye wastes. In this study, among soluble microbial products, chicken egg white (CEW) proteins were selected as simulated contaminants. ES was applied to capture heavy metal ions (e.g., Cu2+ and Zn2+) and the formed eggshell metal (ES-M) complex was use to absorb soluble microbial products (e.g., soluble proteins), followed by subsequent removal of dyes from aqueous solutions using ES-M-CEW adsorbent. The experimental conditions for the adsorption of CEW proteins by ES-M include shaking rate, adsorption pH, isothermal and kinetic studies. The maximum protein adsorption by ES-Zn and ES-Cu were 175.67 and 153.65 mg/g, respectively. Optimal removal efficiencies of the ES-M-CEW particles for Acid Orange (AO7) and Toluidine blue (TBO) dyes were at pH 2 and 12, respectively, achieving performance of 75.38 and 114.18 mg/g, respectively. The removal of TBO dye by ES-M-CEW adsorbent was equilibrated at 5 min. The results showed that low cost and simple preparation of the modified ES particles are feasible for treating various wastewaters.
The technical feasibility of TiO2-photocatalysis towards palm oil mill effluent (POME) treatment is well-proven in previous studies. As a continuity, current study evaluated the strengths, weaknesses, opportunities and threats (SWOT) in a concise manner, subsequently discussed its practicality in palm oil industry of Malaysia. Indeed, TiO2-photocatalysis displays a promising technical feasibility in treating POME, but its wide application is economically-suppressed. It is positing that biological-based treatments (including the existing open-ponding system) are more likely to be employed as the major treating approach for POME over TiO2-photocatalysis. This is particularly true as biological-based treatments offer better performance index for concentrated POME with comparatively lower treatment cost and technicality needed. Furthermore, it is also prevailed with high biogas generability, therefore being irreplaceably benchmarked for POME treatment in Malaysia. Instead of replacing biological treatment entirely, the adoption of TiO2-photocatalysis as complementing tertiary treatment for biological-treated-POME is more practical, bestowed to its robust organic-mineralizing feature for low concentration POME. Such integrated system is expected to augment the POME degradation efficiency, hence effectively preserve the environment from POME pollution.
Zeolite socony mobil-5 (ZSM-5) is a common catalyst used for biomass pyrolysis. Nevertheless, the quantitative information on the catalytic behavior of ZSM-5 on biomass pyrolysis is absent so far. This study focuses on the catalytic pyrolysis phenomena and mechanisms of biomass wastes using ZSM-5 via thermogravimetric analyzer and pyrolysis-gas chromatography/mass spectrometry, with particular emphasis on catalytic level identification and aromatic hydrocarbons (AHs) formation. Two biomass wastes of sawdust and sorghum distillery residue (SDR) are investigated, while four biomass-to-catalyst ratios are considered. The analysis suggests that biomass waste pyrolysis processes can be divided into three zones, proceeding from a heat-transfer dominant zone (zone 1) to catalysis dominant zones (zones 2 and 3). The indicators of the intensity of difference (IOD), catalytic effective area, catalytic index (CI), and aromatic enhancement index are conducted to measure the catalytic effect of ZSM-5 on biomass waste pyrolysis and AHs formation. The maximum IOD occurs in zone 2, showing the highest intensity of the catalytic effect. The CI values of the two biomass wastes increase with increasing the biomass-to-catalyst ratio. However, there exists a threshold for sawdust pyrolysis, indicating a limit for the catalytic effect on sawdust. The higher the catalyst addition, the higher the AHs proportion in the vapor stream. When the biomass-to-catalyst ratio is 1/10, AHs formation is intensified significantly, especially for sawdust. Overall, the indexes conducted in the present study can provide useful measures to identify the catalytic pyrolysis dynamics and levels.
Tetracycline (TC), a popularly found drug pollutant, can be contaminated in food and aquatic regions and causes a severe impact on human health. In this research, a visible light active p-stannic oxide/n-copper manganate (p-SnO2/n-CuMnO2) heterojunction was synthesized and has been applied for a signal on photoelectrochemical sensing of antibiotic TC. Firstly, the n-SnO2 microrods were synthesized via a simple and efficient homogeneous precipitation method and the p-CuMnO2 nanoparticles were synthesized by a facile ultrasound-assisted hydrothermal method. The SnO2/CuMnO2 microrods p-n heterojunction was prepared through a simple impregnation method and physicochemical properties of the microrods are characterized by using X-ray diffraction (XRD), Raman, Brunauer-Emmett-Teller (BET), Fourier-transform infrared (FTIR), UV-Vis diffuse reflectance spectroscopy (UVDRS), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Mott-Schottky analyses. The photoelectrochemical sensing performance of SnO2/CuMnO2 microrods was 2.7 times higher than that of as-synthesized pure SnO2 microrods is due to the more visible light absorption ability and p-n heterojunction (synergy). The designed SnO2/CuMnO2/ITO sensor gives photocurrent signals for the detection of TC in the range of 0.01-1000 μM with the detection limit (LOD) of 5.6 nM. The practical applicability of the sensor was monitored in cow milk and the Taipei River water sample.
Phytochemicals refer to active substances in plant-based diets. Phytochemicals found in for example fruits, vegetables, grains and seed oils are considered relatively safe for consumption due to mammal-plant co-evolution and adaptation. A number of human diseases are related to oxidative stress caused by for example chemical environmental contaminants in air, water and food; while also lifestyle including smoking and lack of exercise and dietary preferences are important factors for disease development in humans. Here we explore the dietary sources of antioxidant phytochemicals that have beneficial effects on oxidative stress, cardiovascular and neurological diseases as well as cancer. Plant-based diets usually contain phenolic acids, flavonoids and carotenoids, which have strong antioxidant properties, and therefore remove the excess of active oxygen in the body, and protect cells from damage, reducing the risk of cardiovascular and Alzheimer's disease. In most cases, obesity is related to diet and inactivity and plant-based diets change lipid composition and metabolism, which reduce obesity related hazards. Cruciferous and Allium vegetables are rich in organic sulphides that can act on the metabolism of carcinogens and therefore used as anti-cancer and suppressing agents while dietary fibres and plant sterols may improve intestinal health and prevent intestinal diseases. Thus, we recommend a diet rich in fruits, vegetables, and grains as its content of phytochemicals may have the potential to prevent or improve a broad sweep of various diseases.
Recently, supercritical fluid CO2 extraction (SFE) has emerged as a promising and pervasive technology over conventional extraction techniques for various applications, especially for bioactive compounds extraction and environmental pollutants removal. In this context, temperature and pressure regulate the solvent density and thereby effects the yield, selectivity, and biological/therapeutic properties of the extracted components. However, the nature of plant matrices primarily determines the extraction mechanism based on either density or vapor pressure. The present review aims to cover the recent research and developments of SFE technique in the extraction of bioactive plant phytochemicals with high antioxidant, antibacterial, antimalarial, and anti-inflammatory activities, influencing parameters, process conditions, the investigations for improving the yield and selectivity. In another portion of this review focuses on the ecotoxicology and toxic metal recovery applications. Nonpolar properties of Sc-CO2 create strong solvent strength via distinct intermolecular interaction forces with micro-pollutants and toxic metal complexes. This results in efficient removal of these contaminants and makes SFE technology as a superior alternative for conventional solvent-based treatment methods. Moreover, a compelling assessment on the therapeutic, functional, and solvent properties of SFE is rarely focused, and hence this review would add significant value to the SFE based research studies. Furthermore, we mention the limitations and potential of future perspectives related to SFE applications.
This study reports the application of hydrated lime for the effective adsorption of the heavy mercury metal from the aqueous phase solutions. Initially, hydrated lime was subjected to structural characterization and thermal stability analysis. The FT-IR spectrum analysis revealed that the existence of the O-H bonds as a confirmation of hydrated lime formation. Subsequently, the XRD powder-based analysis demonstrated that most of the hydrated lime is pure crystalline material known as Portlandite while a small amount of calcite is also present in the structure of the hydrated lime. The thermal stability analysis revealed that the hydrated lime is highly thermally stable under harsh conditions without decomposing at higher temperatures up to 500 °C. Furthermore, the hydrated lime was subjected to the selective adsorption of heavy metal mercury to investigate the potential influence of the adsorbent particle size and loading on adsorption capacity. The results demonstrated that the decrease in the adsorbent particle size leads to the improvement in the mercury adsorption attributing to the rise in specific surface area. The enhancement in the loading of the adsorbent resulted in a reduction in mercury adsorption directing to the fact that already adsorbed metal ions onto the adsorbent surface lead to hindrance for the adsorption of other ions of heavy metal. These results lead to a significant impact on modern in inventing different adsorbents with promising water treatment efficiency for more industrial applications and the related recovery of mercury.
Most developing countries in the world face the common challenges of reducing air pollution and advancing the process of sustainable development, especially in China. Air pollution research is a complex system and one of the main methods is through numerical simulation. The air quality model is an important technical method, it allows researchers to better analyze air pollutants in different regions. In addition, the SCB is a high-humidity and foggy area, and the concentration of atmospheric pollutants is always high. However, research on this region, one of the four most polluted regions in China, is still lacking. Reviewing the application of air quality models in the SCB air pollution has not been reported thoroughly. To fill these gaps, this review provides a comprehensive narration about i) The status of air pollution in SCB; ii) The application of air quality models in SCB; iii) The problems and application prospects of air quality models in the research of air pollution. This paper may provide a theoretical reference for the prevention and control of air pollution in the SCB and other heavily polluted areas in China and give some1inspirations for air pollution forecast in other countries with complex terrain.
This work incorporated technological values into Zn2Cr-layered double hydroxide (LDH), synthesized from unused resources, for removal of pyrophosphate (PP) in electroplating wastewater. To adopt a resource recovery for the remediation of the aquatic environment, the Zn2Cr-LDH was fabricated by co-precipitation from concentrated metals of plating waste that remained as industrial by-products from metal finishing processes. To examine its applicability for water treatment, batch experiments were conducted at optimum M2+/M3+, pH, reaction time, and temperature. To understand the adsorption mechanisms of the PP by the adsorbent, the Zn2Cr-LDH was characterized using Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses before and after adsorption treatment. An almost complete PP removal was attained by the Zn2Cr-LDH at optimized conditions: 50 mg/L of PP, 1 g/L of adsorbent, pH 6, and 6 h of reaction. Ion exchange controlled the PP removal by the adsorbent at acidic conditions. The PP removal well fitted a pseudo-second-order kinetics and/or the Langmuir isotherm model with 79 mg/g of PP adsorption capacity. The spent Zn2Cr-LDH was regenerated with NaOH with 86% of efficiency for the first cycle. The treated effluents could comply with the discharge limit of <1 mg/L. Overall, the use of the Zn2Cr-LDH as a low-cost adsorbent for wastewater treatment has contributed to national policy that promotes a zero-waste approach for a circular economy (CE) through a resource recovery paradigm.
Many microbial species causing infectious disease all over the world became a social burden and creating threat among community. These microbes possess long lifetime, enhancing mortality and morbidity rate in affected organisms. In this condition, the treatment was ineffective and more chances of spreading of infection into other organisms. Hence, it is necessary to initiate infection control efforts and prevention activities against multidrug resistant microbes, to reduce the death rate of people. Seriously concerning towards this problem progress was shown in developing significant drugs with least side effects. Emergence of nanoparticles and its novelty showed effective role in targeting and destructing microbes well. Further, many research works have shown nanocomposites developed from nanoparticles coupled with other nanoparticles, polymers, carbon material acted as an exotic substance against microbes causing severe loss. However, metal and metal oxide nanocomposites have gained interest due to its small size and enhancing the surface contact with bacteria, producing damage to it. The bactericidal mechanism of metal and metal oxide nanocomposites involve in the production of reactive oxygen species which includes superoxide radical anions, hydrogen peroxide anions and hydrogen peroxide which interact with the cell wall of bacteria causing damage to the cell membrane in turn inhibiting the further growth of cell with leakage of internal cellular components, leading to death of bacteria. This review provides the detailed view on antibacterial activity of metal and metal oxide nanocomposite which possessed novelty due to its physiochemical changes.
Iron-doped titanium dioxide loaded on activated carbon (Fe-TiO2/AC) was successfully synthesized from oil palm empty fruit bunch (OPEFB) using sol-gel method. The properties of the synthesized pure TiO2, Fe-doped TiO2, AC, TiO2/AC and Fe-TiO2/AC were examined by various techniques such as field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and nitrogen adsorption-desorption analyses at 77 K. FE-SEM revealed that Fe-doped TiO2 particles were dispersed homogeneously on the AC surface. FT-IR demonstrated high surface hydroxylation after Fe doping on TiO2 and UV-Vis DRS showed that Fe-TiO2/AC had the lowest band gap energy. Catalytic performance results proved that Fe dopants could restrict the recombination rate of hole and electron pairs, whereas AC support improved the Malachite Green (MG) adsorption sites and active sites of the hybrid catalyst. Photocatalytic degradation of 100 mg/L MG in the presence of 1.0 g/L 15 wt% Fe-TiO2 incorporated with 25 wt% AC, initial solution pH of 4 and 3 mM H2O2 could achieve the highest removal efficiency of 97% after 45 min light irradiation. This work demonstrates a promising approach to synthesis an inexpensive and efficient Fe-TiO2/AC for the photocatalytic degradation of organic dye.
The cost-effective and eco-friendly approaches are needed for decontamination of polluted soils. The bio-electrochemical system, especially microbial fuel cells (MFCs) offer great promise as a technology for remediation of soil, sediment, sludge and wastewater. Recently, soil MFCs (SMFCs) have been attracting increasing amounts of interest in environmental remediation, since they are capable of providing a clean and inexhaustible source of electron donors or acceptors and can be easily controlled by adjusting the electrochemical parameters. In this review, we comprehensively covered the principle of SMFCs including the mechanisms of electron releasing and electron transportation, summarized the applications for soil contaminants remediation by SMFCs with highlights on organic contaminants degradation and heavy metal ions removal. In addition, the main factors that affected the performance of SMFCs were discussed in details which would be helpful for performance optimization of SMFCs as well as the efficiency improvement for soil remediation. Moreover, the key issues need to be addressed and future perspectives are presented.
Domestic wastewater has been generated massively along with rapid growth of population and economic. Biological treatment using sequencing batch reactor (SBR) augmented with palm oil fuel ash (POFA) was investigated for the first time. The performance of POFA in enhancing biological treatment of wastewater has not been tested. The porosity property of POFA can improve SBR efficiency by promoting growth of mixed liquor suspended solids (MLSS) and formation of larger flocs for settling and facilitating attachment of microorganisms and pollutants onto POFA surfaces. The properties of POFA were tested to identify morphological properties, particle size, surface area, chemical compositions. Four SBRs, namely SBR1, SBR2, SBR3 and SBR4 were provided with aeration rate of 1, 2, 3 and 4 L/min, respectively. Each reactor was augmented with different dosages of POFA. Optimum aeration rate and POFA concentration were identified by the performance of SBRs in removing chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N) and colour from domestic wastewater. The results showed the most efficient COD (97.8%), NH3-N (99.4%) and colour (98.8%) removals were achieved at optimum POFA concentration of 4 g/L in SBR and aeration rate of 1 L/min. The study also found that higher aeration rate would contribute to the smaller specific size of flocs and decrease the pollutant removal efficiency.
Actinoplanes sp. A1094 strain had been selected for its high production of acarbose from 20 different strains of Actinoplanes sp. can be found in wild. The content for glucosidase inhibitor of acarbose concentration was recorded at 1.12 g/L. The conducted analysis of 16S rRNA sequence of Actinoplanes sp. A1094 showed 99% similar identity to the corresponding sequence of Actinoplanes hulinensis. Acarbose was purified from Actinoplanes hulinensis 1094 with a yield of 8.48%, purity of 98% and further identified by LC/MS and NMR methods (C25H43NO18; m/z: 645.6 g/mol). The purified acarbose was used to evaluate the hypoglycemia in streptozotocin (STZ)-induced diabetic mice model. The purified acarbose reduced postprandial blood glucose level in comparison with Glucobay® as medication for control type 2 diabetes in a combination therapy. Notably, the outcomes of native acarbose on fasting blood glucose levels in mice resemble akin to the commercial product and the acarbose accumulating fermentation and metabolic engineering from the cell gene in which would reduce in production cost. Therefore, acarbose from Actinoplanes hulinensis 1094 could be potentially used to make products for the treatment of type II diabetes.
The present work investigates the feasibility of aerobic granulation for the treatment of low-medium strength domestic wastewater for long-term operation and effects of a static mixer on the properties and removal performances of the aerobic granules formed. The static mixer was installed in a sequential batch reactor to provide higher hydrodynamic shear force in enhancing the formation of the aerobic granules. Aerobic granules were successfully formed in the domestic wastewater, and the granulation treatment system was sustained for a period of 356 days without granules disintegration. Subsequent to the installation, aerobic granules with a low SVI30 of 41.37 mL/gTSS, average diameter 1.11 mm, granular strength with integrity coefficient 10.4% and regular shape with minimum filamentous outgrowth were formed. Mineral concentrations such as Fe, Mg, Ca and Na as well as composition of protein and polysaccharide in tightly bound-extracellular polymeric substance of the aerobic granules were found to be higher under the effect of the static mixer. However, no significant improvement was observed on the TCOD, NH4+-N and TSS removal performance. Good TCOD and TSS removal performance of above 85% and 90%, respectively and moderate NH4+-N removal performance of about 60% were observed throughout the study. Higher simultaneous nitrification and denitrification (SND) efficiency of 56% was observed after the installation of the static mixer, as compared to 21% prior. Therefore, it may be concluded that the installation of the static mixer significantly improved the properties of aerobic granules formation and SND efficiency but not the TCOD, NH4+-N and TSS removal performance.
Size-segregated airborne fine (PM2.1) and coarse (PM>2.1) particulates were measured in an urban environment over central Indo-Gangetic plain in between 2015 and 2018 to get insights into its nature, chemistry and sources. Mean (±1σ) concentration of PM2.1 was 98 (±76) μgm-3 with a seasonal high during winter (DJF, 162 ± 71 μgm-3) compared to pre-monsoon specific high in PM>2.1 (MAMJ, 177 ± 84 μgm-3) with an annual mean of 170 (±69) μgm-3. PM2.1 was secondary in nature with abundant secondary inorganic aerosols (20% of particulate mass) and water-soluble organic carbon (19%) against metal enriched (25%) PM>2.1, having robust signature of resuspensions from Earth's crust and road dust. Ammonium-based neutralization of particulate acidity was essentially in PM2.1 with an indication of predominant H2SO4 neutralization in bisulfate form compared to Ca2+ and Mg2+-based neutralization in PM>2.1. Molecular distribution of n-alkanes homologues (C17-C35) showed Cmax at C23 (PM2.1) and C18 (PM>2.1) with weak dominance of odd-numbered n-alkanes. Carbon preference index of n-alkanes was close to unity (PM2.1: 1.4 ± 0.3; PM>2.1: 1.3 ± 0.4). Fatty acids (C12-C26) were characterized with predominance of even carbon with Cmax at n-hexadecanoic acid (C16:0). Low to high molecular weight fatty acid ratio ranged from 2.0 (PM>2.1) to 5.6 (PM2.1) with vital signature of anthropogenic emissions. Levoglucosan was abundant in PM2.1 (758 ± 481 ngm-3) with a high ratio (11.6) against galactosan, emphasizing robust contribution from burning of hardwood and agricultural residues. Receptor model resolves secondary aerosols and biomass burning emissions (45%) as the most influential sources of PM2.1 whereas, crustal (29%) and secondary aerosols (29%) were found responsible for PM>2.1; with significant variations among the seasons.
Photocatalytic remediation of industrial water pollution has courted intense attention lately due to its touted green approach. In this respect, Keggin-based polyoxometalates (POMs) as green solid acids in photocatalytic reaction possess superior qualities, viz. unique photoinduced charge-transfer properties, strong photooxidative-photoreductive ability, high chemical and thermal stability, and so forth. Unfortunately, it suffers from a large bandgap energy, low specific surface area, low recoverability, and scarce utilization in narrow absorption range. Therefore, the pollutant degradation performance is not satisfactory. Consequently, multifarious research to enhance the photocatalytic performance of Keggin-based POMs were reported, viz. via novel modifications and functionalizations through a variety of materials, inclusive of, inter alia, metal oxides, transition metals, noble metals, and others. In order to advocate this emerging technology, current review work provides a systematic overview on recent advancement, initiated from the strategized synthetic methods, followed by hierarchical enhancement and intensification process, at the same time emphasizes on the fundamental working principles of Keggin-based POM nanocomposites. By reviewing and summarizing the efforts adopted global-wide, this review is ended with providing useful outlooks for future studies. It is also anticipated to shed light on producing Keggin-based POM nanocomposites with breakthrough visible- and solar-light-driven photocatalytic performance against recalcitrant organic waste.
A unidirectional flow solar photocatalytic fuel cell (PFC) was successfully developed for the first time to offer alternative for electricity generation and simultaneous wastewater treatment. This study was focused on the synthesis of α-, δ- and β-MnO2 by wet chemical hydrothermal method for application as the cathodic catalyst in PFC. The crystallographic evolution was performed by varying the ratios of KMnO4 to MnSO4. The mechanism of the PFC with the MnO2/C as cathode was also discussed. Results showed that the catalytic activity of MnO2/C cathode was mainly predominated by their crystallographic structures which included Mn-O bond strength and tunnel size, following order of α- > δ- > β-MnO2/C. Interestingly, it was discovered that the specific surface areas (SBET) of different crystal phases did not give an impact on the PFC performance. However, the Pmax could be significantly influenced by the micropore surface area (Smicro) in the comparison among α-MnO2. Furthermore, the morphological transformation carried out by altering the hydrothermal duration demonstrated that the nanowire α-M3(24 h)/C with 1:1 ratio of KMnO4 and MnSO4 yielded excellent PFC performance with a Pmax of 2.8680 μW cm-2 and the lowest Rint of 700 Ω.