Preparation Of Porous Ni-M-CeO₂?M=Mo?W?P? Composite Coatings By Electrodeposition And Study On Their Catalytic Performance For Hydrogen Evolution

As the cleanest and most environmentally friendly renewable secondary energy source,hydrogen energy is restricted mainly by the production of the cheap hydrogen source and the safety of hydrogen storage technology.Electrocatalytic hydrogen production is considered to be the most effective method for continuous hydrogen production,in which Ni-based materials?Ni-Mo,Ni-W,Ni-P,etc.?are common catalytic hydrogen evolution electrodes.At the same time,according to Brewer-Engel valence bond theory,rare earth oxides have empty d-orbital or f-orbital,which can form a synergistic effect of electrocatalytic hydrogen evolution with metal or alloy with a pair of d electron to enhance the catalytic hydrogen evolution activity of the material.Therefore,Ni-P-CeO₂,Ni-Mo-CeO₂ and Ni-W-CeO₂ composite coatings were prepared by electrodeposition technology in this paper.The hydrogen evolution performance of the prepared coatings was studied by polarization curve?LSV?,AC impedance?EIS?,Tafel curve,constant potential I-t curve and cyclic voltammetry curve?CV?.The specific research results are as follows:1.Ni-P-CeO₂ composite coatings were prepared by composite electrodeposition.The results show that Ni-P exists in amorpHous form in the coatings.The porous Cu template has a three-dimensional foam structure.The structure has a large specific surface area.After adding porous Cu template,the catalytic hydrogen evolution performance of the coating is improved.After electrodepositing Ni-P-CeO₂ composite coating on the template surface,needle-like copper dendrites become spHerical.When the concentration of nano-CeO₂ particles is 20g/L,the Ni-P-CeO₂ composite electrode has the best electrocatalytic activity for hydrogen evolution.The exchange current density?j₀?of Ni-P-CeO₂?20g/L?composite coating is 5.4 times that of Ni-P coating.When the cathodic overpotential is greater than 149mV,the catalytic activity of Ni-P-CeO₂?20g/L?composite coating is higher than that of noble metal platinum.This shows that Ni-P-CeO₂ composite coating is a low cost and efficient non-noble metal hydrogen evolution catalyst.2.In order to further improve the electrocatalytic hydrogen evolution activity of Ni-Mo coating,Ni-Mo-CeO₂ composite coating was prepared by composite electrodeposition to study the effect of nano-CeO₂ content on hydrogen evolution activity of the coating.The results show that Ni-Mo alloy exists in the form of MoNi₄ crystal in the plating layer.The surface of Cu dendrite after electrodepositing Ni-Mo coating and Ni-Mo-CeO₂ composite coating is porous,pores are uniformly distributed on the surface of the coating,and the whole surface of the coating has larger roughness,which is beneficial to reducing the current density during hydrogen evolution on the electrode surface.Ni-Mo-CeO₂ composite coating shows better electrocatalytic activity than its corresponding Ni-Mo binary alloy.Ni-Mo-CeO₂ composite coating has better electrocatalytic hydrogen evolution activity than Ni-Mo coating due to the synergistic effect of hydrogen evolution between nano-CeO₂ particles and Ni-Mo alloy.3.The effect of nano-CeO₂ particles on the surface morpHology and catalytic hydrogen evolution of Ni-W alloy coating was studied.The results show that W element dissolves into Ni lattice to form Ni-W solid solution.The electrocatalytic hydrogen evolution activity of Ni-W-CeO₂composite electrode first increased and then decreased with the increase of the content of nano-CeO₂ particles.Ni-W-CeO₂?10g/L?composite electrode showed the best electrocatalytic hydrogen evolution activity.The constant potential I-t curve and cyclic voltammogram test of Ni-W-CeO₂?10g/L?composite electrode show that the composite coating has good stability.The electrocatalytic activity of Ni-W-CeO₂ composite electrode is higher than that of Ni-W electrode due to the synergistic effect of catalytic hydrogen evolution between Ni-W alloy and nano-CeO₂particles.In summary,the effect of rare earth oxide on hydrogen evolution performance of Ni-based coatings is judged by adding nano-CeO₂ particles to Ni-P,Ni-Mo and Ni-W coatings.It has been found through testing that the catalytic hydrogen evolution performance of all coatings is improved to different extents after adding rare earth oxides.It is further proved that a synergistic effect of catalytic hydrogen evolution can be formed between nickel-based alloys and rare earth oxides,thus enhancing the catalytic hydrogen evolution activity of nickel-based alloy in alkaline solution.