| With the environmental pollution getting worse globally, people has been realized the significance of clean energy. Among various renewable energy and clean energy, hydrogen is one of most ideal clean energy, it has arosed different countries’ attention and also caused extensive research boom in academia because of its higher combustion efficiency, rich resources, no pollution, relatively inexpensive cost and so on. Among all of the approaches for the synthesis of hydrogen, water electrolysis is one of the most common method. What are distinct is that it has higher electrolytic efficiency and considerable product purity and so on. However, because of the high energy consumption caused by the overpotential of hydrogen evolution reaction (HER), it can’t be widespread in commercial application. Therefore, efficient electrocatalysts will be critical to the development of hydrogen evolution technology.At present, the most commonly used hydrogen evolution electrodes are still the platinum metals belonging to the low overpoential metals, which are with the higher catalytic activity for the HER. Because of its expensive and less reserves on earth, so theirs application in industry on a large scale was restrained. Aiming at the shortcomings of platinum-based catalysts, nano-tungsten carbide improved Pt-WC/C and AuPdPt-WC/C noble metallic composite catalysts of the HER were studied.Nano-tungsten carbide was prepared by intermittent microwave heating method (IMH) in this study. IMH has many advantages such as heating uniformity, rapid increase of temperature in heating, and easy to control. The morphology, composition and crystal structure of the catalyst were characterized by XRD, SEM EDS and TEM. The results showed that tungsten carbide prepared by IMH was uniformly dispersed and the average particle size was about50nm. Compared with the tungsten carbide obtained by common high temperature heating, the one prepared by IMH usually has higher surface area and smaller particle size. Also, we tested its performance for the HER in the acidic media, it showed that only when the overpotential of HER on the WC was higher than300mV, could the electrocatalyst show some electrochemical catalytic activity.Nano-tungsten carbide promoted composite catalyst Pt-WC/C for the HER was prepared by IMH and the direct chemical reducion methods. The results showed that Pt-WC/C electrocatalyst has higher activity in acidic solution compared to the commercial Pt/C electrocatalyst and the micron-tungsten carbide promoted Pt-WC/C electrocatalyst, performing a lower overpotential and a higher exchange current density. Despite of Pt-WC/C electrocatalyst with lower Pt loading, but its catalytic activity was enhanced significantly compared with the commercial Pt/C electrocatalyst which using more Pt. This study phenomena showed that the synergistic effect between Pt and WC.In addition, Pt-WC/C was modified by adulterating Au and Pd transition metals, obtaining AuPdPt-WC/C electrocatalyst, and the composite electrocatalysts was tested for the HER in the acidic media for the first time. The results showed that when the overpotential of HER was0.3V, the current density of AuPdPt-WC/C was150mA/cm2higher than Pt-WC/C electrocatalyst, that is the catalytic HER performance of AuPdPt-WC/C electrocatalyst was improved a lot. These effects on the catalytic activity for the HER by changing electrolyte concentration and environmental temperature were discussed. When the mass ratio Au:Pd:Pt:WC was1:1:2:1, the composite electrocatalysts owns the best catalytic activity of the HER. Kinetic study showed that the HER on the AuPdPt-WC/C electrocatalyst gave a lower overpotential in H2SO4solution with higher concentration. In a certain temperature range, the hydrogen evolution performance could also be enhanced by raising the environmental temperature. |
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