Efficient Hydrogen Production on Crystalline-Amorphous Heterostructured Cobalt Boride-Phosphite Electrocatalyst

Targeted phase engineering of nanomaterials through non-equilibrium synthesis strategies provides a rich platform for the development and tuning of nanostructured catalysts with outstanding properties and life-time. Unconventional phases or even complex heterostructures play a crucial role in the performance of catalysts for efficient water electrolysis. By utilizing a controlled, iterative reduction synthesis route, a tailored binder-free cobalt boride-phosphite electrode (CoxB-[0.2]P-O) with mixed crystalline-amorphous phases is developed. The tailored cobalt chemistry, hierarchical morphology and mixed phases synergistically enhance the catalytic activity for hydrogen evolution reaction (HER). Those electrodes exhibit platinum-like HER performance with an overpotential of 33 mV at the standard current density of 10 mA cm-2, with excellent intrinsic kinetics and enhanced electron transfer in an alkaline 1M KOH electrolyte. Comprehensive microstructure and spectroscopic analyses proved the success of the one-pot strategy to modulate the chemistry of cobalt by incorporating boron and phosphite. Moreover, the tailored formation of nanostructures with locally varying morphology by the co-existence of amorphous and crystalline phases on the nanometer scale is confirmed. This approach facilitates the rational design for tuning the metal boride-based catalysts’ activity for hydrogen evolution by tailored chemistry of the metal active centers and thus the phase engineering of similar nanomaterials while avoiding the necessity of any post-synthesis thermal treatment processes.