Role of Synergistic Effect in Oxygen Evolution Reaction over Layered Double Hydroxide

Layered double hydroxides (LDHs) has played an important role in the field of catalysis because of its high dispersion of active sites, adjustable layer elements, and exchangeable interlayer anions. LDHs show excellent catalytic activity in oxygen evolution reaction (OER), due to the specific synergistic effect of double metals site. Thus, it is crucial to reveal the role of synergistic effect for promoting catalytic performance of photocatalyst and electrocatalyst. Although great efforts from experimental workers have been devoted to exploring the types and ratios of bimetals in LDHs, the role of synergistic effect on OER is still unclear. In this work, we systematically investigated the synergistic mechanism and the role of synergistic effect on OER performances based on density functional theory calculation plus U (DFf -FU) method. Five kinds of LDHs (M32+N3+-LDH (M2+ =Co2+, Ni2+; N3+ =Al3+, Cr3+, Mn3+, Fe3+)) were built to study the synergistic effect from different bimetal. The results showed that oxygen species is bridged by one M2+ and one N3+ metal, forming a stable adsorption structure. For electrocatalytic OER, the synergistic effect of the bimetallic sites decreased the free energy change of the potential-determining step, and further reduces the overpotential of the electrocatalytic oxygen evolution reaction. Therein, Ni3Fe-LDH has the lowest overpotential, exhibiting superior electrocatalytic OER activity among the five LDHs. This is not the case in photocatalytic OER, the synergy of bimetals affects the band gap, work function and driving force of LDHs, which determine the ability of LDH photocatalytic OER. The five types of LDH studied are all visible light response, and Ni3Cr-LDH is predicted to be a good OER photocatalyst in view of its higher driving force than the overpotential. This work reveals the synergistic effect of bimetal in LDH on OER activity from a micro-atomic level, which will provide theoretical insights for the design of novel LDH-based catalysts.