多孔二元过渡金属纳米片阵列电极制备及电催化析氢研究

Preparation of Porous Binary Transition Metal Nanosheets Array Electrode and Its Electrocatalytic Hydrogen Evolution

碱性电解液中,电解水析氢的H_(2)O解离过程非常缓慢,造成析氢反应较高的过电位和Tafel效率.选择具有本征高析氢活性的合金催化剂与水解离中心-过渡金属氧化物复合,并进一步优化复合物形貌结构,被证明是解决这个科学问题的重要策略.我们报道一例新颖的二元过渡金属纳米片阵列自支撑电极(MoO_(3-x)-MoNi_(4)@NF),多孔MoO_(3-x)纳米片阵列均匀生长在泡沫镍电极表面,纳米片表面镶嵌着MoNi_(4)合金纳米颗粒,多孔的纳米片阵列使得催化剂具有高的比表面积(57 m^(2)/g)和丰富的活性位点.在碱性电解液中(1 mol/L KOH),MoO_(3-x)-MoNi_(4)@NF仅需要过电位30 mV就能达到10 mA·cm^(-2)电流密度,如此低的过电位超过了贵金属催化剂20%Pt/C(32 mV).同时,MoO_(3-x)-MoNi_(4)@NF具有超低的Tafel斜率,仅为31 mV dec^(-1),如此低的Tafel斜率得益于Ni-Mo合金与MoO_(3-x)之间的协同催化剂作用的发挥,MoO_(3-x)可以有效促进H_(2)O解离并释放Hads,MoNi_(4)纳米颗粒作为Hads吸脱附位点可以促进H_(2)生成,这使得该催化剂有望替代贵金属铂用作碱性电催化析氢领域.

In alkaline electrolyte,the water dissociation kinetics is sluggish,resulting in high overpotential and Tafel slope.It has been proved that it is an important strategy to select the alloy catalyst with intrinsic high hydrogen desorption activity to combine with the transition metal oxide of water dissociation center and further optimize the morphology and structure of the complex.A novel self-supporting electrode based on binary transition metal nanosheet arrays is reported(MoO_(3-x)-MoNi_(4)@NF).The porous MoO_(3-x) nanosheets arrays were uniformly grown on the surface of the nickel foam,and the MoNi_(4) nanoparticles were embedded on the surface of the nanosheets.The porous nanosheets arrays made the catalyst have high specific surface area(57 m^(2)/g)and abundant active sites.In alkaline electrolyte(1 mol/L KOH),MoO_(3-x)-MoNi_(4)@NF only required overpotential of 30 mV to reach the current density of 10 mA·cm^(-2),which even exceeds 20%Pt/C(32 mV).At the same time,the Tafel slope of MoO_(3-x)-MoNi_(4)@NF is only 31 mV dec^(-1),such a low Tafel slope is due to the synergetic catalyst effect between Ni-Mo alloy and MoO_(3-x),MoO_(3-x) can effectively promote the dissociation of H_(2)O and release Hads.MoNi_(4) nanoparticles as the desorption sites of Hads can promote H_(2) generation,which makes the catalyst be expected to replace platinum as the field of alkaline electrocatalytic hydrogen evolution.