Modulation of Active Sites Induced by CoP via Mn Doping Enables Multifunctional Electrocatalytic Hydrogen Evolution, Oxygen Evolution, and Biomass Oxidation Reactions

Abstract

Achieving hydrogen production via overall and coupled water splitting (OWS and CWS) based on renewable electricity is a promising manner for accomplishing “carbon neutrality”. However, rare catalysts can simultaneously accommodate catalytic properties of hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and biomass oxidation reaction (5-hydroxymethylfurfural oxidation reaction, HMFOR); particularly, there is an unsatisfactory trade-off between OER and HMFOR. Herein, the active sites are rationally modulated through Mn doping in CoP, synchronously catalyzing HER, OER, and HMFOR. Experimental and theoretical results reveal that the incorporation of Mn upshifts the d-band center, which facilitates the adsorption of water molecules and H* species on the electron-rich P site for promoting HER. More importantly, Mn accelerates the catalyst reconstruction to generate Mn-CoOOH active species for both OER and HMFOR. Particularly, the energy barrier of the rate-determining step for OER is diminished at the Mn site. Besides, the OH* adsorption at the Mn site and the HMF adsorption at the Co site are concurrently consolidated for boosting HMFOR. Consequently, the optimized Mn0.15-CoP/CC catalyst exhibits low cell voltages of 1.62 and 1.45 V to 143 mA cm−2 for OWS and CWS. This work showcases a promising route to realize multifunctional catalysts via doping strategies for efficient green hydrogen production systems.