Rational design of hierarchical MOF ‐derived CoP @ Co‐Fe LDH bifunctional electrocatalyst: An approach toward efficient overall water splitting in alkaline media

Abstract

The electrodes that are inexpensive, had high catalytic activity, and can be easily produced in situ on a conductive substrate have been studied extensively to produce hydrogen through water splitting. Herein, a Co-Fe layered double hydroxide (Co-Fe LDH) and a metal-organic framework (MOF)-derived cobalt phosphide (CoP) are combined to fabricate a catalyst without any binders on a conductive carbon cloth (CC) that has abundant surface area and flexibility. The prepared electrode is then applied to the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in 1 M KOH electrolyte and the overpotentials necessary to reach 10 mA/cm2 are 172 and 270 mV, respectively. Moreover, the Tafel slopes are 39 and 79 mV−1 for OER and HER, respectively, thereby outperforming Co-Fe LDH and CoP individually. The potential needed to reach 10 mA/cm2 is 1.66 V in overall water splitting using the two-electrode configuration. Notably, the catalytic activity is not degraded even after 50 hours of operation. Characterizations demonstrate that the combination of Co-Fe LDH and CoP based on the catalyst and the strong coupling effect among the Co, Fe, and P active sites account for the excellent HER and OER performances. Our suggested in situ method represents a novel route for the preparation of hierarchical MOF-derived CoP@Co-Fe LDH (hierarchical CoP@Co-Fe LDH) composite on conductive CC-based high-performance electrocatalysts for overall water splitting.