Optimized trimetallic benzotriazole-5-carboxylate MOFs with coordinately unsaturated active sites as an efficient electrocatalyst for the oxygen evolution reaction.

Exploring efficient and stable oxygen evolution reaction (OER) catalysts with earth-abundant elements has been an urgent task in water splitting. Metal-organic frameworks (MOFs), possessing abundant active metal sites and tunable porous crystalline structures, are promising as OER catalysts. In this paper, a MOF based on benzotriazole-5-carboxylate (Co3-btca) that contains unsaturated coordinated metal centers and a 1D channel was selected to act as an OER catalyst. To optimize the OER performance, isostructural bimetallic and trimetallic frameworks were obtained by doping with Fe and/or Ni ions. The optimized Co2.36Fe0.19Ni0.45-btca possesses the lowest overpotential of 292 mV at 10 mA cm-2 and a small Tafel slope of 72.6 mV dec-1. The enhanced catalytic performance could be attributed to the synergistic effect between the unsaturated coordinated Co, Fe and Ni sites, which are beneficial for the nucleophilic attack of OH- forming adsorption intermediates.