Hydrogen production via artificial photosynthesis relies on highly active, stable catalysts for both the water oxidation and hydrogen evolution reactions. To address this need, we have synthesized manganese-based WOC and nickel-based HERC via cyclic voltammetry (CV). We have developed a new electrodeposition method involving multiple series of CV over different potential ranges to synthesize MnOx WOCs in situ on conductive surfaces. The resulting catalytic film has a unique nanoscale fibrous surface morphology. Functionality tests showed an onset potential of ~1.0V vs. Ag/AgCl and excellent effectiveness towards water oxidation. Its stability was assessed by consecutive CV and long term amperometry experiments, with the results showing very stable catalytic performance over long periods of time. We have also synthesized a Ni/NiO catalyst for the hydrogen evolution reaction using CV scans over a single potential range. The resulting film has a surface morphology consisting of a monolayer of firmly-packed walnut-shaped spherical particles with diameters of 0.1~0.2 μm. We tested its functionality in both neutral and alkaline media using CV, and showed that it promotes hydrogen evolution. Assessments also showed a stable performance during 200 consecutive CV scans, and in long term amperometry experiments. Finally, we have built a small device by coating MnOx and Ni/NiO catalysts on FTO substrates to produce an anode and cathode, respectively. The device has successfully achieved the water splitting reaction, powered only by a single AA battery.

Solar-driven water splitting by manganese- and nickel-based catalysts synthesized by cyclic voltammetry

252nd National Meeting (2016)

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