Rapid synthesis of size-tunable transition metal carbide nanodots under ambient conditions

Transition metal carbides (TMCs) have attracted great interest due to their potential for application in energy conversion and electrocatalysis. However, their nanostructures are difficult to control, especially in the case of TMC nanodots since their growth process usually requires high carburization temperature which could cause easy agglomeration of small size nanoparticles. Here, we develop a microwave combustion method for rapid (similar to 2 min) synthesis of TMC nanodots with tunable size from similar to 3 to similar to 40 nm under ambient conditions. These TMC nanodots exhibit outstanding catalytic performance for the hydrogen evolution reaction (HER) with low onset overpotentials of 19 and 27 mV vs. RHE as well as small Tafel slopes of 39 and 45 mV dec(-1) in H2SO4 and KOH, respectively. This work highlights a novel strategy for the design and synthesis of transition metal carbides.