Phosphorus-doped MoS_(2) with sulfur vacancy defects for enhanced electrochemical water splitting

具有硫空位的磷掺杂二硫化钼用于增强电化学水分解

MoS_(2)is a promising electrocatalyst because of its natural abundance and outstanding electrochemical stability.However,the poor conductivity and low activity limit its catalytic performance;furthermore,MoS_(2)is unable to satisfy the requirements of most industrial applications.In this study,to obtain a P-doped MoS_(2)catalyst with S vacancy defects,P is inserted into the MoS_(2)matrix via a solid phase ion exchange at room temperature.The optimal P-doping amount is 11.4 wt%,and the resultant catalyst delivers excellent electrocatalytic properties for the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)with the corresponding overpotentials of 93 and 316 mV at 10 mA cm^(-2) in an alkaline solution;these values surpass the overpotentials of most previously reported MoS_(2)-based materials.Theoretical calculations and results demonstrate that the synergistic effect of the doped P,which forms active centers in the basal plane of MoS_(2),and S vacancy defects caused by P doping intensifies the intrinsic electronic conductivity and electrocatalytic activity of the catalyst.Density functional theory calculations demonstrate that P optimizes the free energy of the MoS_(2)matrix for hydrogen adsorption,thereby considerably increasing the intrinsic activity of the doped catalyst for the HER compared with that observed from pristine MoS_(2).The enhanced catalytic activity of P-doped MoS_(2)for the OER is attributed to the ability of the doped P which facilitates the adsorption of hydroxyl and hydroperoxy intermediates and reduces the reaction energy barrier.This study provides a new environmentally friendly and convenient solid-phase ion exchange method to improve the electrocatalytic capability of two-dimensional transition-metal dichalcogenides in largescale applications.

由于其丰度高、电化学稳定性强,MoS_(2)被认为是一种极具前途的电催化剂.然而,其导电性差和活性低,因此催化性能受到限制.此外,MoS_(2)无法满足工业化大规模应用的要求.本工作中,为了获得具有S空位缺陷的P掺杂MoS_(2)催化剂,我们在室温下通过固相离子交换将P插入到MoS_(2)基体中.当P掺杂量为11.4 wt%时为最佳,所制备的催化剂具有优异的电催化析氢(HER)和析氧(OER)性能.碱性条件下,在10 mA cm^(-2)电流密度下对应的过电位分别为93和316 mV,这些数值超过了先前报道的大多数二硫化钼基材料的过电位.理论计算和实验结果都表明,MoS_(2)基面上形成的掺杂P活性中心及由P掺杂引起的S空位缺陷的协同作用增强了催化剂的本征电子电导率和电催化活性.密度泛函理论计算表明,与原始的MoS_(2)相比,P优化了MoS_(2)氢吸附自由能,从而显著提高了掺杂后催化剂对HER的固有活性.P掺杂MoS_(2)对OER的催化活性增强归因于掺杂P促进羟基和含氧中间体的吸附及反应能垒的降低.本研究提出了一种全新、环保、便捷的固相离子交换法来提高二维过渡金属硫族化合物在大规模应用中的电催化能力.