One-pot solvothermal synthesis of highly catalytic Janus transition metal phosphides (TMPs) for high performance OER

Abstract

Green hydrogen is a highly efficient and affordable energy carrier for imminent energy supply. First time, this work demonstrates the crystalline TMPs synthesized by one-pot solvothermal method. M12P5 (M = Ni, Co, Ni-Co) nanoparticles deposited on conducting surface of nickel foam (M12P5@NF) serving as highly auspicious oxygen evolution reaction (OER) electrode. Our findings demonstrate that the M12P5@NF electrodes can be cast-off as capable Janus catalysts for OER. The onset potential for OER of Janus Co12P5 befalls at 1.29 VRHE and possesses a current density of 10 mAcm−2 just at overpotential of only 160 mV. Intriguingly, Co12P5 reveals the low Tafel slope value of 33 mVdec−1. The onset potential for Ni12P5, (Ni-Co)12P5 electrodes are 1.30 and 1.46 VRHE, decade current density obtained just at bias of 300 and 340 mV, respectively. These electrocatalysts unveil the worthy electro-active zone, as compared to that of other reported nickel and cobalt based materials. These electrocatalysts also sustain an amazing stability during long-term stability experiments. Ni, Co and (Ni-Co)-phosphides show high TOF value of 8.5, 11.37 and 5.1 s−1and mass activity of 119, 68 and 48 A g−1 respectively at over potential of 350 mV which is an indicative of rapid electrochemical reaction and charge transfer kinetics of electrocatalyst. The catalytic enactment of Co12P5 is several folds superior than avant-garde catalysts (RuO2 and IrO2) under the similar set of conditions. The greater OER activity of M12P5 at such low overpotential is attributed to the mutual consequence of high electroactive sites at exterior of catalytic surface and auspicious interaction generated among intrinsically dynamic 3d-transition metal i.e. Ni, Co and phosphorous.TMPs are efficient and non-precious metal centered materials, which unwraps new prospects to exploit water electrolysis for green hydrogen fuel.