The recycling and treatment of wastewater using microbial fuel cells (MFCs) has been attracting significant attention as a way to control energy crises and water pollution simultaneously. Despite all efforts, MFCs are unable to produce high energy or efficiently treat pollutants due to several issues, one being the anode's material. The anode is one of the most important parts of an MFC. Recently, different types of anode materials have been developed to improve the removal rate of pollutants and the efficiency of energy production. In MFCs, carbon-based materials have been employed as the most commonly preferred anode material. An extensive range of potentials are presently available for use in the fabrication of anode materials and can considerably minimize the current challenges, such as the need for high quality materials and their costs. The fabrication of an anode using biomass waste is an ideal approach to address the present issues and increase the working efficiency of MFCs. Furthermore, the current challenges and future perspectives of anode materials are briefly discussed.
Sodium phenoxide is a potentially promising hydrogen storage material due to its high hydrogen capacity and enhanced thermodynamic properties. Nevertheless, efficient catalysts are still lacking due to the high kinetic barrier for the reversible hydrogen uptake and release of sodium phenoxide. In the current work, a comparative study on the catalytic hydrogenation of sodium phenoxide was conducted. To our delight, a simple yet effective ruthenium-based catalyst was identified to respond aggressively to hydrogen in the solid-state hydrogenation of sodium phenoxide even at room temperature. The activity was enhanced by 6 fold with the as-synthesized 5.0% Ru/TiO2 catalyst as compared to that with commercial 5.0% Ru/Al2O3, respectively, under the same conditions.
One of the world's challenging energy issues is introducing practical and affordable technology for organosulfur removal in fuel. Adsorptive desulfurization (ADS) can address this issue if highly effective activated carbon (AC) derived from industrial waste with excellent textural properties is used. In this study, the derived ACs from glycerin pitch loaded with P and Fe (AC/P and AC/Fe) were used as adsorbents for the ADS of model fuel oils, such as dibenzothiophene (DBT) at mild operating conditions. Under the optimized experimental conditions, 0.3 g of adsorbent dosage, 60 min reaction time, 30 °C temperature, and pH 4, the maximal DBT removal of 96.28 and 43.64%, respectively, for AC/P and AC/Fe was realized. The results indicated that the phosphorus-doped AC/P increases the selectivity of the ADS mechanism for DBT removal. Kinetic investigations disclosed that the adsorption process follows second-pseudo-order kinetics and the Langmuir adsorption isotherm model. The adsorbents remained active for five successive reuses, indicating their robust real-world applications. The electrochemical properties of the fabricated carbon electrodes were analyzed via cyclic voltammetry by coating the ACs with polytetrafluoroethylene (PTFE) as a binder. The transition-metal-doped AC/Fe, though exhibiting 5 times lower surface area, showed the highest specific capacitance at a scan rate of 5 mVs-1 (0.65 μF cm-2). Similarly, the extended AC:PTFE capacitor at a 10% binder ratio offered the maximum capacitance value (1.13 μF cm-2). The synthesized ACs demonstrated potential application as an electrode material, and hence glycerin pitch could be a low-cost precursor to improve the feasibility of commercial production of AC.
The lack of efficient hydrogen storage material is one of the bottlenecks for the large-scale implementation of hydrogen energy. Here, a series of new hydrogen storage materials, i.e., anilinide-cyclohexylamide pairs, are proposed via the metallation of an aniline-cyclohexylamine pair. DFT calculations show that the enthalpy change of hydrogen desorption (ΔHd) can be significantly tuned from 60.0 kJ per mol-H2 for the pristine aniline-cyclohexylamine pair to 42.2 kJ per mol-H2 for sodium anilinide-cyclohexylamide and 38.7 kJ per mol-H2 for potassium anilinide-cyclohexylamide, where an interesting correlation between the electronegativity of the metal and the ΔHd was observed. Experimentally, the sodium anilinide-cyclohexylamide pair was successfully synthesised with a theoretical hydrogen capacity of 4.9 wt%, and the hydrogenation and dehydrogenation cycle can be achieved at a relatively low temperature of 150 °C in the presence of commercial catalysts, in clear contrast to the pristine aniline-cyclohexylamine pair which undergoes dehydrogenation at elevated temperatures.
Hydrazine borane (HB) is a chemical hydrogen storage material with high gravimetric hydrogen density of 15.4 wt%, containing both protic and hydridic hydrogen. However, its limitation is the formation of unfavorable gaseous by-products, such as hydrazine (N2H4) and ammonia (NH3), which are poisons to fuel cell catalyst, upon pyrolysis. Previous studies proved that confinement of ammonia borane (AB) greatly improved the dehydrogenation kinetics and thermodynamics. They function by reducing the particle size of AB and establishing bonds between silica functional groups and AB molecules. In current study, we employed the same strategy using MCM-41 and silica aerogel to investigate the effect of nanosizing towards the hydrogen storage properties of HB. Different loading of HB to the porous supports were investigated and optimized. The optimized loading of HB in MCM-41 and silica aerogel was 1:1 and 0.25:1, respectively. Both confined samples demonstrated great suppression of melting induced sample foaming. However, by-products formation was enhanced over dehydrogenation in an open system decomposition owing to the presence of extensive Si-O···BH3(HB) coordination that further promote the B-N bond cleavage to release N2H4. The Si-OH···N(N2H4) hydrogen bonding may further promote N-N bond cleavage in the resulting N2H4, facilitating the formation of NH3. As temperature increases, the remaining N-N-B oligomeric chains in the porous silica, which are lacking the long-range structure may further undergo intramolecular B-N or N-N cleavage to release substantial amount of N2H4 or NH3. Besides open system decomposition, we also reported a closed system decomposition where complete utilization of the N-H from the released N2H4 and NH3 in the secondary reaction can be achieved, releasing mainly hydrogen upon being heated up to high temperatures. Nanosizing of HB particles via PMMA encapsulation was also attempted. Despite the ester functional group that may favor multiple coordination with HB molecules, these interactions did not impart significant change towards the decomposition of HB selectively towards dehydrogenation.