Structural Regulation And Electrocatalytic Hydrogen Evolution Performance Of Ruthenium-based Two-dimensional Nanomaterials

Currently,the optimal pH-universal electrocatalysts for hydrogen evolution reaction(HER)are still limited to low abundance and prohibitive Pt-based catalysts,impeding their commercial applications.Noble metal-Ruwith 4%price of Pt has been considered as the most promising candidate for HER owing to the similar bond strength with hydrogen to that of Pt.However,the HER activity is still inferior to that of benchmark Pt catalyst.Moreover,Rucatalyst faced the problem of dissolution under operational electrolytes,resulting in a significant decline in catalytic activity.Herein,development of an effective method to improve the activity and stability of Ru-based catalyst is of great significance for promoting the development of H₂ production application.Based on the above,this paper is designed to improve the catalytic activity and stability of Ruby constructing Ru-based heterogeneous,thus achieving HER activity close to or even exceed optimal 20%commercial Pt/C,and mechanism of Ru-based composites were deeply explored.The main contents are as follows:(1)In this work,Ru³⁺ions were immobilized and dispersed in alginate,achieved by the virtue of the complexation of SA with polyvalent metal cations to form nanoconfined“egg box”structure.After freeze-drying,RuP/Ruheterogeneous nanosheet(RuP/RuNS)HER electrocatalysts was prepared via a facile oxidation and vapor phosphatizing process.The obtained RuP/RuNS shows excellent HER performance and stability over a wide pH range.Specifically,constructed RuP/RuNS requires ultralow overpotentials of 13,25,and28 mV at 10 mA·cm^-2 in 1 M KOH,0.5 M H₂SO₄,and 1 M phosphate buffer saline media,respectively,which was comparable to or even better than 20.0%Pt/C.Importantly,RuP/RuNS maintained catalytic activity of?90.0%after electrochemical stability tests at all pH values.Density functional theory(DFT)was used to calculate the reaction energy barriers and electron distribution at different sites of RuP/Ruheterojunction.The DFT results show that there is a strong electron interaction between RuP and Ruheterointerface,which optimizes the electron configuration of RuP in RuP/Ru,resulting in RuP sites of RuP/Ruhas more moderate water dissociation energy and H adsorption energy.(2)Despite of excellent HER activity of RuP/Ru,there is a problem of excessive Ruloading.To reduce the loading of Ruspecies in catalysts while maintaining high HER activity over a wide pH range,introducing low-cost transition metal(such as Co,Fe,Ni,Cu)into Rubased catalysts to form heterogeneous metal phosphates have been considered as a feasible strategy.Motivated by such findings,we introduced Co²⁺into the precursor solution.By adjusting the Ru³⁺/Co²⁺ion ratio,the RuP₃/CoP heterogeneous nanosheets(RuP₃/CoP NS)with different Ruloads were obtained.Among them,RuP₃/CoP NS catalyst with 15.0%Ruloading requires low overpotentials of 60,81 and 25 mV at 10 mA·cm^-2 in0.5 M H₂SO₄,1 M phosphate buffer saline and 1.0 M KOH,respectively.In addition,RuP₃/CoP NS-15.0%showed extremely excellent stability at the wide pH range.DFT calculation results show that the P(CoP)site of RuP₃-CoP is the highly active site of the catalyst in both acidic and alkaline media.RuP₃ can regulate the electronic environment around the P atoms in the CoP and optimize the reaction energy barrier,so that RuP₃/CoP has high catalytic activity at all pH values.