为开发新型廉价高效的析氢材料,用恒电流复合电沉积方法制各了(Ni-Mo)-TiO_2复合电极,讨论了TiO_2悬浮量和电沉积时间对电极催化析氢性能的影响.用XRD和SEM对电极的晶体结构和表面形貌进行了表征,以稳态极化曲线对电极的催化析氢特性进行了评价.结果表明,(Ni-Mo)-TiO_2电极是纳米TiO_2粒子相和纳米晶Ni-Mo固溶体相构成的复合电极.电极具有较高的催化析氢活性.在25℃、0.5 mol·dm~(-3)H_2SO_4溶液中其表观交换电流密度是Ni-Mo合金电极的2.6倍,是Ni电极的60倍.在电流密度为100 mA·cm~(-2)时,电极电势相对于Ni-Mo电极正移了120 mV,相对于Ni电极正移了542 mV.催化活性的提高源于反应机理的改变,表观活化吉布斯自由能相对于Ni-Mo合金电极降低了24.48 kJ·mol~(-1).
(Ni-Mo)-TiO_2 composite coating was prepared by electrolytic co-deposition of Ni-Mo ally and TiO_2 particles on a Cu substrate from a solution in which TiO_2 nano particles(P-25)were suspended by stiring.Effects of concentration of TiO_2 particles suspended in the plating bath and depositing time on the catalytic activity for the hydrogen evolution reaction(HER)were discussed.The surface morphology and microstructure of(Ni-Mo)-TiO_2 coating were observed by SEM and XRD.Catalytic activity for HER was evaluated on the basis of electrochemical steady-state polarization curves in 0.5 mol·dm-3 H2SO4 solution.Results indicate that the(Ni-Mo)-TiO_2 electrode consists of TiO_2 crystalline and Ni-Mo nano crystalline in solid solution.The composite electrode has better catalytic activity compared with Ni-Mo and Ni alloy electrodes.The polarization over potential for hydrogen evolution of the(Ni-Mo)-TiO_2 electrode is 120 mV lower than that of Ni-Mo electrode and iS 542 mV lower than that of Ni electrode at the current density of 100 mA·cm~(-2).The apparent exchange current density of the composite electrode is 2.6 times that of the Ni-Mo electrode,and 60 times that of Ni electrode.The increasing catalytic activity for HER of the (Ni-Mo)-TiO_2 composite electrode is mainly due to the change in the reaction mechanism.The apparent Gibbs free energy of activation of the composite electrode is 24.48 kJ·mol~(-1) lower than that of Ni-Mo electrode.
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