钴/铬共掺杂协同增强NiS的尿素电氧化性能OA

During the process of hydrogen production from water-splitting assisted by the urea oxidation reaction(UOR),developing a high-performance nickel-based catalyst for UOR is a key challenge that must be addressed urgently to enhance hydrogen production efficiency.In this work,the Co/Cr co-doped nickel sulfide composite(Co,Cr-NiS/CC)was prepared on carbon cloth(CC)by the hydrothermal-calcination method.The composition,morphology,structure,and surface chemical state of the composite were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission elec-tron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).The electrochemical perfor-mance of the composite was tested in the electrolyte of 1.00 mol·L-1 KOH and 0.33 mol·L-1 urea.Meanwhile,density functional theory(DFT)calculations were conducted on the NiS(001)and Co,Cr-NiS(001)models.The structure-activity relationship was revealed through the analysis of the density of states(DOS),the d-band center,and the energy barrier of the rate-determining step(RDS)for the UOR.Electrochemical tests demonstrate that the Co,Cr-NiS/CC composite exhibits excellent catalytic activity for UOR.Specifically,at the current densities of 100 A·m-2 and 1 000 A·m-2,the required potentials are 1.321 V and 1.378 V,respectively,which are lower than those of the other control samples.At a potential of 1.527 V,after 200 h of chronoamperometry(CA)testing,the retention rate of current density is 64.83%.DFT calculations indicate that the co-doping of Co and Cr enhances the intensity of the DOS at the Fermi energy(EF)of the composite,shifts the d-band center of the composite upwards,reduces the energy barrier of the RDS of UOR to 0.331 eV,and optimizes the electronic struc-ture of NiS and the adsorption energy of reaction intermediates.This work proposes a new approach to constructing an efficient non-metallic UOR catalyst.