Improving the Efficiency of Water Splitting and Oxygen Reduction Via Single-Atom Anchoring on Graphyne Support

Single-atom catalysts(SACs)have received significant interest for optimizing metal atom utilization and superior catalytic performance in hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and oxygen reduction reaction(ORR).In this study,we investigate a range of single-transition metal(STM_(1)=Sc_(1),Ti_(1),V_(1),Cr_(1),Mn_(1),Fe_(1),Co_(1),Ni_(1),Cu_(1),Zr_(1),Nb_(1),Mo_(1),Ru_(1),Rh_(1),Pd_(1),Ag_(1),W_(1),Re_(1),Os_(1),Ir_(1),Pt_(1),and Au_(1))atoms supported on graphyne(GY)surface for HER/OER and ORR using first-principle calculations.Ab initio molecular dynamics(AIMD)simulations and phonon dispersion spectra reveal the dynamic and thermal stabilities of the GY surface.The exceptional stability of all supported STM_(1)atoms within the H1 cavity of the GY surface exists in an isolated form,facilitating the uniform distribution and proper arrangement of single atoms on GY.In particular,Sc_(1),Co_(1),Fe_(1),and Au_(1)/GY demonstrate promising catalytic efficiency in the HER due to idealisticΔG_(H^(*))values via the Volmer-Heyrovsky pathway.Notably,Sc_(1)and Au_(1)/GY exhibit superior HER catalytic activity compared to other studied catalysts.Co_(1)/GY catalyst exhibits higher selectivity and activity for the OER,with an overpotential(0.46 V)comparable to MoC_(2),IrO_(2),and RuO_(2).Also,Rh_(1)and Co_(1)/GY SACs exhibited promising electrocatalysts for the ORR,with an overpotential of 0.36 and0.46 V,respectively.Therefore,Co_(1)/GY is a versatile electrocatalyst for metal-air batteries and water-splitting.This study further incorporates computational analysis of the kinetic potential energy barriers of Co_(1)and Rh_(1)in the OER and ORR.A strong correlation is found between the estimated kinetic activation barriers for the thermodynamic outcomes and all proton-coupled electron transfer steps.We establish a relation for the Gibbs free energy of intermediates to understand the mechanism of SACs supported on STM,/GY and introduce a key descriptor.This study highlights GY as a favorable single-atom support for designing highly active and cost-effective versatile electrocatalysts for practical applications.