Oxygen evolution reaction(OER) is one of the two half-reactions in water splitting. Sustainable OER is an essential prerequisite in hydrogen production from water. In the past few years, many research efforts have been directed towards the development of electrocatalysts for OER, which are based on noble metals and transition metal oxides. But these materials suffer from poor conductivity. Recently, it has been found that, transition metal chalcogenide materials, especially Ni- and Co- based compounds, can catalyze OER efficiently. However, the research on these systems is at the very beginning, and few syntheses of Ni_1-xCo_xSe nanocrystals (NCs) have been reported in the literature till now. Herein, we report a simple colloidal synthesis approach to grow ternary Ni_1-xCo_xSe NCs with tunable composition and study their OER properties. The phase of the nanocrystals is hexagonal irrespective of their composition. The composition of Ni and Co in the NCs can be easily controlled by tuning the experimental parameters. By performing OER on samples with different Ni/Co ratio, we optimized the composition for obtaining high performance OER. The best performing samples exhibit a catalytic OER current of 10 mA/cm2 at a small overpotential of 1.5 V vs. RHE with extended long-term stability. The detailed results will be presented in the meeting.

Figure. (a) TEM image of Ni_0.37Co_0.74Se and (b) Polarization curves of OER for NCs with different Ni/Co ratios