Deposition Laws And Preparation Technology Studies On High-performance Electrode Materials For Hydrogen Evolution

The energy crisis and a series of environmental problems, which were resulted from the depletion of the fossil fuel have become a serious obstacle for the survival and development of our future generations. Hydrogen energy is a kind of efficient, environmentally friendly and renewable energy, which attracted widespread attention. Back in the80s of the last century, people have depicted a "hydrogen economy" era blueprint for us, in which hydrogen would be the main energy. One of the main methods for large-scale hydrogen production is water electrolysis, but the cathode has high hydrogen evolution overpotential and the anode material has high oxygen evolution overpotential, which leads to excessive energy consumption. This thesis not only studied the electrodeposition laws of Ni-Mo alloys in alkaline citrate solution, and prepared Ni-Mo, Ni-Mo-W alloy by new electrodeposition preparation technics, but also studied the electrochemical properties of Ni-Mo, Ni-Mo-W for hydrogen evolution reaction in30wt%KOH solution, and characterized electrodes byXRD, SEM and EDS.The electrodeposition laws of Ni-Mo alloys were studied by the methods of electrochemistry. Polarization curves obtained by potentiostatic deposition and the testing of coating component content, cyclic voltammogram indicated that Mo could not deposite separately without induce metal, Ni deposited earlier in solution contained Ni2+and MoO42-than which only contained Ni2+, However, in the lower electrode potential, the deposition current efficiency of Ni-Mo alloy in solution which contained Ni2+and MoO42-was lower than the deposition current efficiency of Ni in solution contained Ni2+alone. Rotating disk electrode test results indicated that Ni deposition process was controlled by diffusion-charge transfer process, the Ni-Mo codeposition process was controlled by charge transfer step.Ni-Mo alloy electrode was prepared in the deposition solution which ammonia was instead by glycine by electrodeposition. The influence of all technics parameters on the catalytic activity of hydrogen evolution of the Ni-Mo alloy were studied systematically, then the optimal technics parameters for preparation of the electrode were fixed. The performance of Ni-Mo alloy prepared under conditions of optimal technics parameters was studied, SEM observation showed that the surface of the alloy coating had a large number of small projections, which greatly improved the specific surface area of the electrode; EDS elemental analysis results proved that the composition of the alloy was Ni80.14MO19.59; The XRD diffraction showed that the Ni-Mo alloy existed a certain degree of amorphous structure; Tafel test results showed that Ni-Mo alloys had high hydrogen evolution catalytic activity, under the same conditions, Ni-Mo alloy electrode overpotential η100was152mV, which was293mV lower than foam Ni electrode.Based on the new preparation technics for the preparation of Ni-Mo alloy, ternary alloys of Ni-Mo-W were prepared by the method of electrochemical deposition. The catalytic activity for hydrogen evolution of the Ni-Mo-W alloy electrode which were prepared by electrodeposition were studied by orthogonal experiments and single factor experiments, and the optimal technics parameters were fixed. The performance of Ni-Mo-W alloy prepared under conditions of optimal technics parameters was studied, SEM observation showed that the surface of the alloy coating containing a large number of uniform size small projection, which greatly improved the specific surface area of the electrode; EDS elemental analysis results proved that the composition of the coating is Ni79.73Mo18.35W1.92; The electrochemical performance test results showed that Ni-Mo-W had higher hydrogen evolution catalytic activity than Ni-Mo alloy, the overpotential η100of Ni-Mo-W alloy was123mV, which was29mV lower than Ni-Mo alloy; AC impedance test results showed that although the specific surface area of the Ni-Mo-W alloy was slightly smaller than Ni-Mo alloy, but its true exchange current density was2.36times as much as Ni-Mo alloy.