Ammonium Metatungstate Applied in Excellent HER Catalyst

Sustainable energy sources are crucial in the modern world, where conventional fossil fuels contribute towards an alarming percentage of hazardous pollutants in the environment. Hydrogen is a non-polluting fuel and a replenishable energy source, able enough to take the edge of an energy crisis. Noble metal platinum (Pt) has been proved to be the most effective electrocatalyst for hydrogen evolution reaction (HER). However, the high price of Pt limits its applications.

Tungsten carbide (WC) is a catalyst having the platinum-like behavior, by doping with platinum, makes it an excellent transition metal compounds composite catalyst. Thus, ammonium metatungstate (AMT) is applied in excellent HER catalyst, the as-synthesized 3%Pt/WC/C10 catalyst behaves the most excellent synthetically electrocatalytic performance like commercial 10%Pt-C. The preparation method of the tungten based catalysts is as following steps:

The synthesis of WC/C10 was by annealing. First, weighed some P123 into a beaker with 60 mL deionized water, then added a certain amount of glucose under magnetic stirring, which keeped 30 min at room temperature (25 °C), and the theoretical weight ratio of P123 and glucose was 5:95. Used 2 M hydrochloric acid to adjust the pH value of the mixture solution to 1. Thereafter, a number of ammonium metatungstate was dissolved in the above solution, and the nominal molar ratio of WC:C was 1:10. The whole mixture was dried in an oven at 80 °C until it became brownish black, the solid was transferred into an agate mortar and pestled it to form the particles with uniform size. Afterwards, the samples were calcinated at 30 °C for 1 h under an Ar atmosphere in order to get rid of the air inside the tube, and then heated up to 900 °C for 3 h.

The 3%Pt/WC/C10 catalyst was prepared as follow: First, Measure 10 mg/ml chloroplatinic acid solution 390 μL, then added 100 mL deionized water, plus 46 mg WC/C10, and the Pt loading was controlled at 3 wt% to the supports. After ultrasonic mixing for 30 min, the suspension continued to be stirred for 24 h at 400 rpm to form a homogeneous mixture at 25 °C, followed by drying in an oven at 60 °C.

In summary, ammonium metatungstate is applied in excellent HER catalyst, the as-synthesized 3%Pt/WC/C10 catalyst behaves the most excellent synthetically electrocatalytic performance. The as-synthesized 3%Pt/WC/C10 catalyst behaves the most excellent synthetically electrocatalytic performance with a small overpotential of 85 mV at 10 mA cm−2 and 129 mV at 30 mA cm−2. The result revealed that the catalytic activity of the 3%Pt/WC/C10 sample is almost same with that commercial 10%Pt/C catalyst, which indicates that the synergistic role of tungsten carbide and platinum can effectively reduce the amount of platinum on the condition of obtaining equivalent electrocatalytic activity. More interesting, the turning of from residual Pt(IV) to Pt(0) during CV cycles helps to improve electrocatalytic stability rather than attenuation of corrosion resistance.

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