Discovering Ce-rich oxygen evolution catalysts, from high throughput screening to water electrolysis

We report a new Ce-rich family of active oxygen evolution reaction (OER) catalysts composed of earth abundant elements, discovered using high-throughput methods. High resolution inkjet printing was used to produce 5456 discrete oxide compositions containing the elements nickel, iron, cobalt and cerium. The catalytic performance of each of these compositions was measured under conditions applicable to distributed solar fuels generation using a three-electrode scanning drop electrochemical cell. The catalytic activity and stability of representative compositions (Ni_(0.5)Fe_(0.3)Co_(0.17)Ce_(0.03)O_x and Ni_(0.3)Fe^(0.07)Co_(0.2)Ce_(0.43)O_x) from 2 distinct regions were verified by resynthesizing these compositions on glassy carbon rods for electrochemical testing. The activity of the new Ce-rich catalysts was further verified using an unrelated synthetic method to electrodeposit a pseudo-ternary composition Ni_(0.2)Co_(0.3)Ce_(0.5)O_x, which produced a catalyst with 10 mA cm^(−2) oxygen evolution current at 310 mV overpotential. The unique Tafel behavior of these Ce-rich catalysts affords the opportunity for further improvement