In-Situ Synthesis Of Cu-Based Nanomaterials And Study Their Electrocatalytic Performances Toward Water-Splitting

The rapid development of society and economy has been accompanied by a large consumption of fossil fuels.The gradual depletion of domestic fossil fuels and the rising price of oil on the international market are putting increasing pressure on the rapidly developing economy and society.The development of a green hydrogen economy is an important way to complete the transformation of the energy structure and to achieve the goal of"carbon peaking"and"carbon neutrality".Electrocatalytic hydrogen production has received a lot of attention because of its clean and efficient advantages.However,in practice,the slow anodic oxygen evolution reaction（OER）greatly limits the efficiency of the catalytic reaction.Combining hydrogen evolution reaction with other oxidation reactions with low potential and fast reaction kinetics（such as,oxidation of hydrogen,hydrazine or ethanol）is an effective way to reduce the overpotential of the anode and achieve low-cost H₂ production.In order to reduce the catalytic reaction energy barrier,the design and synthesis of high performance catalysts is key to facilitate efficient electrocatalytic hydrogen production.In this paper,a series of Ru-doped Cu-based nanostructured catalysts were designed using copper foam as precursors which applied to the study of electrocatalytic hydrolysis troughing strategies such as morphological design,surface modification and metal doping.The main investigations are as follows:（1）An efficient Ru-doped hollow amorphous Cu（OH）_x nanowire catalyst was prepared by etching and solvothermal processes using copper foam as a substrate.The specific hollow structure facilitates the catalytic process by providing an abundance of active channels and active sites.In addition,the amorphous carriers give a wealth of catalytic active sites,thus ensuring good catalytic activity.Ru-Cu（OH）_x/CF has good electrocatalytic activity and robust and good stability over a wide p H range.Ru-Cu（OH）_x/CF has an overpotential of only 45,80 and 50 m V at a current density of10 m A cm^-2 in alkaline,neutral and acidic electrolytes,respectively.The catalytic activity of Ru-Cu（OH）_x/CF were also outperforming many Ru-based electrocatalysts.A two-electrode electrolytic water system assembled with commercial nickel-iron foam and Ru-Cu（OH）_x/CF achieved current densities of 10 m A cm^-2 driven by a smaller voltage（1.59 V）under alkaline conditions.（2）The aim is to avoid problems such as the difficulty in exploring the mechanism and effects of Ru doping due to the complexity of the reaction mechanism.Meanwhile,based on previous studies,Cu-Ru intermetallic interactions were further explored to synthesize more energy-efficient catalysts for hydrogen production.The catalysts in the form of Ru-doped Cu₂O nanospheres stacked in nanochains（Ru-Cu₂O/CF）were prepared on copper foam substrates through surface oxidation reactions,annealing,cathodic reduction reactions and redox reactions with the participation of Ru³⁺.The prepared Ru-Cu₂O/CF catalysts exhibited outstanding HER catalytic activity in both alkaline and neutral electrolytes,as well as significant Hz OR catalytic performance in alkaline electrolytes.It was found that the high specific surface area morphology and the superhydrophilic surface of the material significantly improved the electrocatalytic activity.Further analysis by XRD and XPS spectroscopy revealed that Ru doping significantly modulates the electronic structure of Cu in the material.This Cu-Ru interaction facilitates the optimization of the catalytic reaction kinetics and thus improves the catalytic reaction efficiency.A two-electrode electrolytic device assembled with Ru-Cu₂O/CF as both cathode and anode and 1.0 M KOH+0.5 M N₂H₄ as electrolyte required only 17.4 m V to drive a current density reaction of 10 m A cm^-2.This indicates that the prepared Ru-Cu₂O/CF catalyst has great potential for application in the oxidative coupling of hydrazine hydrate to the total hydrogenolysis reaction for energy-efficient hydrogen production.