Electrochemical production of hydrogen using electricity obtained from renewable sources such as Solar and wind represents an attractive avenue for clean and sustainable energy production and storage. Herein we report a low cost, highly active and stable copper based catalyst for hydrogen evolution reaction (HER) fabricated by chemical solution deposition. The catalyst exhibits self-optimizing behavior under hydrogen evolution conditions. Structural and morphological studies performed on pristine and self-optimized catalyst indicates that it undergoes nanostructuring from porous nanoplates to foam-like interconnected nanowires composed of ultra-small Cu^o nanoparticles (2~3 nm in size) as shown in figure 1. Electrochemical impedance spectroscopy performed after various CV cycles suggests that there is substantial reduction in charge transfer resistance which is associated with large increase in effective double layer capacitance of the catalyst. This agrees well with the morphological analysis, wherein, nanostructuring was observed after CV cycling. A dissolution-reprecipitation based mechanism is suggested to explain the observed morphological changes. The proposed catalyst exhibits hydrogen evolution current of 10 mA/cm² at an overpotential of 105 mV. The detailed results will be presented in the meeting.

Figure 1. a) TEM image of Cu based catalyst after cycling, b) Linear sweep voltammograms of various electrodes obtained at a sweep rate of 10 mV/S