Preparation Of Nickel-based Nanocomposite Catalyst And Its Performance Foe Urea Electrolysis

Hydrogen production from urea electrolysis is an advanced technology,which can also treat the wastewater containing urea.The electrolytic process consists of urea oxidation reaction(UOR)at the anode and hydrogen evolution reaction(HER)at the cathode.However,due to the limitation of kinetics,there is a large overpotential.Hence,efficient catalyst is needed to accelerate the reaction,decrease the overpotential and reduce the energy consumption.Therefore,looking for catalyst with high activity,good stability and low cost is the key to the development of urea electrolysis technology.In this paper,the preparation of nickel based composite catalyst and its performance of urea electrolysis are studied.The main contents are as follows:(1)Asok-like Ni-Ni O-Mo_0.84Ni_0.16/NF hybrid is synthesized via hydrothermal method and calcination.it exhibits superior catalytic activity for UOR(1.29 V at 10 m A cm^–2)and HER(-39.8 m V at-10 m A cm^–2).Furthermore,when used both as cathode and anode catalysts in a two-electrode system for urea electrolysis,it can deliver a current density of10 m A cm^–2 at a cell voltage of 1.37 V and maintain its activity for more than60 h at 150 m A cm^–2.The excellent performance can be mainly attributed to:the unique morphology could enlarge the specific surface area of the catalyst and expose more active sites;the self-supporting structure makes the activity material closely combine with the substrate,ensures the rapid electron transfer,and avoids active substrate falling off,which improve the activity and stability.(2)The tomentum-like Fe Ni₃-MoO₂ heterojunction nanosheets array self-supported on nickel foam(NF)as bifunctional catalyst is prepared by facile hydrothermal and annealing.Only 1.29 V and-50.8 m V is required to obtain±10 m A cm^–2 for UOR and HER respectively,showing great bifunctional catalytic activity.For overall urea electrolysis,it only needs 1.37V to reach 10 m A cm^–2,and can last at 100 m A cm^–2 for 70 h without obvious activity attenuation,showing outstanding durability.Coupling interface constructions of Fe Ni₃-MoO₂ heterostructures,novel morphology with mesoporous and self-supporting structure could be the reason for this good performance.This work thus proposes a promising catalyst for boosting UOR and HER to realize efficient overall urea electrolysis.The results show that the strategies of constructing heterojunction and,morphology control and self-supporting structure can improve the catalyst activity and stability,which provide new methods for the follow-up research.(3)The Ni Se₂-Ni MoO₄ heterojunction nano-ballflower is successfully prepared on NF through facile hydrothermal and selenylation.As a bifunctional catalyst,only 1.32 V and-35.57 m V is required to obtain±10m A cm^–2 for UOR and HER respectively,displaying good catalytic activity.In a two-electrode electrolyzer,only a cell voltage of 1.37 V is required to drive10 m A cm^-2,and it shows robust durability,operating for 100 h without obvious activity attenuation at 150 m A cm^–2.The Ni Se₂-Ni MoO₄heterostructure,Se dropping,novel mesoporous and self-supporting structure could be the reason for this great performance.This work provides a prospective catalyst for promoting H₂ production and urea-containing wastewater treatment.The results show that the combination of Ni Se₂-Ni MoO₄ heterojunction structure,porous spheroidal morphology and self-supporting structure can optimize the electronic structure,increase the specific surface area and avoid the catalyst falling off during the test.These strategies are helpful to improve the activity and stability of the catalyst,and provide the basis for the preparation of the catalyst with excellent performance.