An increase in the necessity for clean and renewable energy leads to the production of hydrogen by several methods. Splitting of water by electrolysis is catching up to be a productive method to produce pure hydrogen with low cost and high efficiency using highly active non-noble metal electrocatalysts. MoS 2 has been widely studied for energy conservation devices for its 2D layered structure, excellent electronic conductivity, and high specific surface area. Incorporating transition metals (Co or Ni) will alter the intrinsic characteristic of MoS 2 by enhancing its electrocatalytic property for hydrogen evolution reaction. Hence MoS 2 , CoMoS 2, Co 0.5 MoS 2 and a composite of Co 0.5 MoS 2 with nitrogen sulfur doped graphene oxide were prepared by a facile hydrothermal method. Better performance was observed for the composite of Co 0.5 MoS 2 with N, S-rGO compared to other prepared catalysts with a low onset potential of 85 mV, overpotential (at 10 mA/cm 2 ) of 178 mV and Tafel slope of 63.8 mV/ dec. Further, the stability of the catalyst evaluated by chronoamperometric analysis demonstrated steady electrochemical performance for 12 hours.

Microbial electrolysis cells (MECs) can electrochemically produce green hydrogen from waste streams. However, cathode materials have been a bottleneck for the practical application of MECs due to difficulties in scale-up and high costs. To overcome current drawbacks, we have examined a novel flowable cathode in MECs, where nickel-loaded activated carbon (Ni/AC) powders were suspended in a buffering solution as a cathode without electrode fabrication processes. The Ni/AC flow cathode with higher Ni content and minimum Ni/AC loading (4 Ni-atom% and 0.125 wt-AC.%, Ni4/AC0.125) demonstrated the highest catalytic activities (−0.86 V vs Ag/AgCl at −10 A/m2) among Ni/AC flow cathodes tested. This result indicates that pseudocapacitive behavior toward Faradaic reactions can be promoted by increasing Ni loadings on Ni/AC particles. The MEC with a Ni4/AC0.125 flow cathode produced comparable hydrogen production rates (1.62 ± 0.15 L-H2/Lreactor-day) to the Pt control (1.64 ± 0.09 L-H2/L-day) and 40% higher than the blank (only current collector without Ni/AC, 1.29 ± 0.02 L-H2/L-day) at a 4 h cycle. The impacts of carbon black blending remain unclear; there was a 10% increase in hydrogen production rates with the lowest carbon black content (0.06 wt %) in the Ni/AC flow cathode, but hydrogen production rates were not further improved as carbon black content increased.

The emerging need of clean and renewable energy drives the exploration of effective strategies to produce molecular hydrogen. With the assistance of highly active non-noble metal electrocatalysts, electrolysis of water is becoming a promising candidate to generate pure hydrogen with low cost and high efficiency.[1] This reaction takes place almost exclusively on Pt/C catalysts at the cathode which is expensive and need to be replaced by a metal-based catalyst which can show a comparable HER (Hydrogen evolution reaction) activity. Transition metal oxides, nitrides and sulfides have been widely explored as catalysts for HER and OER (Oxygen evolution reaction) due to their good electronic conductivity, stable and variable oxidation states, and superior corrosion resistance.[2] In this research, MoNi4 embedded MoO3 nanorods are synthesized using facile hydrothermal method. Further, Molybdenum Vanadium Nitride is coated on top the synthesized electrode using RF/DC magnetron co-sputtering.[3] This combination of hydrothermal and magnetron sputtering fabrication methods of the electrodes results in high surface area of the electrodes thereby improving the reaction kinetics of hydrogen production. The performance of the electrodes is tested in N2/O2 saturated 1M KOH solution using steady state technique called Staircase Voltammetry (SCV) instead of conventional dynamic LSV (Linear sweep voltammetry)/CV (Cyclic Voltammetry).[4] This alternative method for testing is performed due to the exaggeration of the catalytic performance through conventional LSV/CV arising from double layer charging for nanostructured electrode. The electrodes are characterized by X-ray diffraction and SEM for structural and morphological analysis. Hence, we report the synthesis of novel MoVN on MoNi4/MoO2 nanorods using DC/RF Magnetron co-sputtering as an efficient, bifunctional, binder free electrode for overall water splitting. The electrode is characterised for both full-cell and half-cell configurations proving its stability for 12 hours. This work provides a reliable approach to the production of low cost and high-effectiveness electrodes for the application in commercial electrolyzers. [1] J. Zhang et al., “Efficient hydrogen production on MoNi4 electrocatalysts with fast water dissociation kinetics,” Nat. Commun., vol. 8, no. May, pp. 1–8, 2017, doi: 10.1038/ncomms15437. [2] L. A. Santillán-Vallejo et al., “Supported (NiMo,CoMo)-carbide, -nitride phases: Effect of atomic ratios and phosphorus concentration on the HDS of thiophene and dibenzothiophene,” Catal. Today, vol. 109, no. 1–4, pp. 33–41, 2005, doi: 10.1016/j.cattod.2005.08.022. [3] B. Wei et al., “Bimetallic vanadium-molybdenum nitrides using magnetron co-sputtering as alkaline hydrogen evolution catalyst,” Electrochemistry Communications, vol. 93. pp. 166–170, 2018, doi: 10.1016/j.elecom.2018.07.012. [4] S. Anantharaj and S. Kundu, “Do the Evaluation Parameters Reflect Intrinsic Activity of Electrocatalysts in Electrochemical Water Splitting?,” ACS Energy Lett., vol. 4, no. 6, pp. 1260–1264, 2019, doi: 10.1021/acsenergylett.9b00686. Figure 1

The emerging need of clean and renewable energy drives the exploration of effective strategies to produce molecular hydrogen. With the assistance of highly active non-noble metal electrocatalysts, electrolysis of water is becoming a promising candidate to generate pure hydrogen with low cost and high efficiency. This reaction takes place almost exclusively on Pt/C catalysts at the cathode which is expensive and need to be replaced by a metal-based catalyst that is cost effective and can show a comparable HER (Hydrogen Evolution Reaction) activity. Transition metal oxides, nitrides and sulfides have been widely explored as catalysts for HER and OER (Oxygen Evolution Reaction) due to their good electronic conductivity, stable and variable oxidation states, and superior corrosion resistance. In this research, MoNi4 embedded MoO3 nanorods are synthesized using facile hydrothermal method. Further, Molybdenum Vanadium Nitride is coated on top the synthesized electrode using RF/DC magnetron co-sputtering. This combination of hydrothermal and magnetron sputtering fabrication methods of the electrodes results in high surface area of the electrodes thereby improving the reaction kinetics of hydrogen production. The performance of the electrodes is tested in N2/O2 saturated 1M KOH solution using steady state technique called Staircase Voltammetry (SCV) instead of conventional dynamic LSV (Linear Sweep Voltammetry)/CV (Cyclic Voltammetry). This alternative method for testing is performed due to the exaggeration of the catalytic performance through conventional LSV/CV arising from double layer charging for nanostructured electrode. The electrodes are characterized by X-ray diffraction and SEM for structural and morphological analysis. Hence, we report the synthesis of novel MoVN on MoNi4/MoO2 nanorods using DC/RF Magnetron co-sputtering as an efficient, bifunctional, binder free electrode for overall water splitting. The electrode is characterised for both full-cell and half-cell configurations proving its stability for 12 hours. This work provides a reliable approach to the production of low cost and high-effectiveness electrodes for the application in commercial electrolyzers.