Superfast Synthesis of Densely Packed and Ultrafine Pt-Lanthanide@KB via Solvent-Free Microwave as Efficient Hydrogen Evolution Electrocatalysts.

At present, it is still a great challenge to synthesize refractory Pt-based electrocatalysts with excellent active specific surface area, specific activity, and stability by a simple method. Here, a superfast and solvent-free microwave strategy is reported to synthesize refractory ultrafine (≈3 nm) Pt-lanthanide@Ketjen Black (PtM@KB, M = La, Gd, Tb, Er, Tm, and Yb) alloy with densely packed as efficient hydrogen evolution electrocatalysts in a domestic microwave oven for the first time. The optimized Pt61 La39 @KB delivers excellent hydrogen evolution reaction (HER) activity with a low overpotential of 38 mV (10 mA cm-2 ) and a high TOF value of 44.13 s-1  (100 mV) in 0.5 m H2 SO4 , and performs well in 1.0 m KOH. This method can also be used to grow catalysts on carbon cloth (CC) directly. PtLa@CC shows an overpotential of 99 mV (1000 mA cm-2 ) in 0.5 m H2 SO4 and can maintain activity after 500 h. Theoretical calculations reveal the enhanced stability and activity owing to the higher vacancy formation energy of Pt atoms and the optimized value of ΔGH* . Solvent-free microwave strategy constitutes a significant insight into the development of refractory electrocatalyst with ultrafine size and highly dense, which can also work well at high current densities.