Iron-Doped Cobalt Monophosphide Nanosheet/ Carbon Nanotube Hybrids as Active and Stable Electrocatalysts for Water Splitting

Developing earth-abundant, active, and stable electrocatalysts for water splitting is a vital but challenging step for realizing efficient conversion and storage of sustainable energy. Here, a multiscale structure-engineering approach to construct iron (Fe) doped cobalt monophosphide (CoP) hybrids for efficient electrocatalysis of water splitting is reported. A two-step method is developed to synthesize CoP nanosheets with uniform Fe doping and hybridization with carbon nanotubes (CNTs). The nanostructuring, uniform doping, and hybridization with CNT afford efficient electrocatalysts comparable to Pt/ C for hydrogen evolution reactions in acidic, neutral, and alkaline electrolytes. It is found that the Fe doping level has different effects on catalytic activities in different electrolytes. Furthermore, after in situ oxidization/hydrolysis of the phosphides to corresponding oxyhydroxides, the hybrid electrocatalysts exhibit better performances than the benchmark commercial Ir/ C for catalyzing the oxygen evolution reaction. A two-electrode alkaline water electrolyzer constructed with these hybrid electrocatalysts can afford a current density of 10 mA cm(-2) at a voltage of 1.5 V.