The Preparation And The Performance Of NiCu@Pd/C Core Shell Electrocatalysts

The way of production of alumina by electrolysis of sodium carbonate is a new technology, which break the traditional Bayer process. The most important process is the membrane electrolysis of sodium carbonate solution, which produces sodium bicarbonate and sodium hydroxide. Existing membrane electrolysis of sodium carbonate is to use the the hydrogen evolution cathode and oxygen evolution anode. Cell voltage is 2.5-2.6V, the power consumption is about 1800-1900 kWh/tAl2O3-So our research propose that hydrogen diffusion anode substitute the oxygen evolution anode, which can significantly reduce the cell voltage. And also, hydrogen produced in cathode can be used into anode, which formed the recycling of hydrogen. Thus, the most important is developing a kind of catalyst with high catalytic activity towards HOR.In this study, we prepared carbon-sxupported core shell nanoparticles with NixCuy cores and Pd rich shells (NixCuy@Pd/C) for hydrogen oxidation reaction. These catalysts had been synthesized by heat treatment to obtain NixCuy/C cores and the polyol reduction to form the Pd shell on NixCuy. We mainly examined the percentage composition of NiCu alloy, the ratios of Ni/Cu, Pd loads, the ability of methanol tolerance, durability and so on. XRD analysis showed that the lattice distance of Pd were greatly dependent on the percentage composition of NiCu alloy, the ratios of Ni/Cu and Pd loads. The TEM image showed that the Ni1Cu4@Pd core shell nanoparticles in size of 6.83±1.2nm were distributed on carbon surface uniformly. As a result, when the percentage composition of NiCu alloy was 20%, the ratios of Ni/Cu was 1:4 and the Pd load was 10%, the catalyst showed the optimal performance for HOR. The HOR performance of Ni1Cu4@Pd/C catalyst was greatly superior to that of Pd/C catalyst and also the methanol tolerance ability of Ni1Cu4@Pd/C catalyst was better than that of Pd/C catalyst. It was mainly because that the interaction between the NiCu alloy and Pd shell, which leaded that the contraction of Pd. The contraction of Pd lattice would increase the d-orbital overlap, contributing to a down shift of the position of the d-band center of Pd. And the down shift of d-band center and the reduced electronic density of Pd atom collectively weaken the overlap between Pt and the CO, avioding the poisoning of the catalyst.Moreover, the’hydrogen cycle’electrolysis of Na2CO3 with hydrogen oxidation anode (HOA) that employing the Ni1Cu4@Pd/C catalyst had exhibited the extremely low cell voltage. Only 0.44V was consumed for electrochemical regeneration of Na2CO3 to NaHCO3 and NaOH at 10mA·cm-2. What’s more, the cell voltage of Ni1Cu4@Pd/C HOA electrolysis decreased significantly from 2.53V,1.38V to 1.09 V at 100 mA cm"2 as compared with conventional electrolysis and Pd/C HOA electrolysis, respectively. The power consumption was about 800 kWh/tAl2P3, which was reduced by 57% compared to the conventional electrolysis, and this had significant meaning to saving energy.