Preparation Of Three-dimensional Ordered Macroporous Mesoporous Ni-S-based Catalyst And Its Electrocatalytic Performance

The non-renewable and highly polluting nature of fossil energy have forced researchers to seek cleaner and more efficient energy.Hydrogen energy is regarded as a promising alternative energy due to its wide range of conversion sources and clean advantages.As the main method of obtaining hydrogen energy,electrolysis of water hydrogen technology cannot achieve large-scale commercial application due to the slow kinetics of the oxygen evolution reaction(OER).The key to solving this problem is the development of suitable electrocatalysts.However,the high cost and scarcity of existing precious metal catalysts hinder their wide application.The transition metal sulfide catalyst can be used as an ideal substitute for the existing noble metal catalysis,due to its advantages of high reserve and good activity.Nevertheless,the shortcomings of porous transition metal sulfide catalysts,such as low specific surface area and disordered channels,have restricted the improvement of OER performance.Herein,specific nanostructures are designed by combining hard template with soft template.And the nickel-sulfur-based catalyst with a three-dimensional ordered macroporous mesoporous structure is successfully prepared by gas-solid phase vulcanization.Moreover,the element types and content of the impregnating precursor are also adjusted to achieve doping of metal elements.This work provides a new idea for the preparation of ordered porous structures and multi-metal element catalysts.The specific experiment contents are as follows:(1)Bying Polymethyl methacrylate(PMMA)as the hard template and surfactant P123 as the soft template,and precursor impregnation,curing,calcination,and subsequent vulcanization,the three-dimensional ordered macroporous mesoporous nickel-sulfur-based catalyst(3DOM/m NiSx)has been successfully prepared,and applied to OER reaction.At the same time,nickel-sulfur-based nanoparticle catalysts(NiSx NPs)is prepared for comparison.The results show that compared with nickel-sulfur-based catalysts of different structures,the performance of 3DOM/m NiS2 is significantly better than that of NiS2 NPs.At a current density of 10 mA Cm-2,the overpotential(η10)is decreased by 45 mV and the Tafel slope is decreased by 61 mV dec-1,which reflects the advantages of three-dimensional ordered macroporous mesoporous structure in improving OER performance;comparing the nickel-sulfur-based catalysts with the same macroporous mesoporous structure,it can be seen that compared with 3DOM/m NiO-NiS2 and 3DOM/m NiS-NiS2,3DOM/m NiS2 with a higher degree of vulcanization has a lower overpotential(η10=340 mV),and the Tafel slope(84 mV dec-1)is also respectively reduced by 24 mV dec-1 and 51 mV dec-1,which is attributed to the properties of sulfide in improving conductivity.(2)Based on the research of 3DOM/m NiS2,by changing the types and content of precursor,3DOM/m FexNi1-xS2 catalysts doped with different molar ratios of Fe were prepared and applied to basic OER reactions.From the results we can know that,the performance of Fe-doped 3DOM/m FexNi1-xS2 catalyst is better than that of 3DOM/m NiS2,which proves that the synergy between iron and nickel metals promotes the electrochemical oxygen evolution reaction;In different molar ratios of Fe doping,3DOM/m Fe0.1Ni0.9S2(X=0.1)has the best OER performance,the overpotential at 10 mA cm-2 is 246 mV,the Tafel slope is 59 mV dec-1,and it has good test stability,which shows that the catalyst has the FeNi ratio with the best catalytic activity.