A co-coordination strategy to realize janus-type bimetallic phosphide as highly efficient and durable bifunctional catalyst for water splitting

Abstract

In this work, a Janus-type dual-ligand metal-organic frameworks derived bimetallic (Fe, Co)P nanoparticles embedded carbon nanotube (CNT) skeleton (DLD-FeCoP@CNT) is presented and synthesized via a facile “co-coordination synthesis” strategy. The DLD-FeCoP@CNT hybrid shows much better performances for OER and HER with much lower Tafel slope of 39.6 (57.1) mV dec-1, an overpotential of 286 (166) mV @ 10 mA cm-2 and better stability for OER (HER) in 1 M KOH. Being both cathode and anode for water splitting, it requires only a low voltage of 1.67 V to obtain 10 mA cm-2 with nearly 100% faradaic efficiency, which is close to Pt/C//RuO2 cell. Density functional theory calculations based on the bimetallic phosphide (Fe0.3Co0.7P) model reveal that, compared with the monometallic FeP or CoP, the enhanced catalytic activities of Fe0.3Co0.7P is mainly manifested in its free energy of H adsorption (ΔGH*) closer to zero, larger binding strength for H2O and higher electrical conductivity.