Crystal phase engineering of CoBOx/NiCoP heterostructures as trifunctional electrocatalysts for overall water splitting and urea electrolysis

Abstract

Rational design of non-precious metal-based catalysts for value-added chemicals production is crucial but still challenging. Herein, a trifunctional electrocatalyst with heterostructures is developed via phosphating and NaBH4 pretreatment of the pristine ZIF-L for overall water splitting and urea oxidation. The as-prepared CoBOx/NiCoP catalyst exhibits superior electrocatalytic performance with only overpotentials of 100, 283 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to reach the current density of 10 and 100 mA cm−2, respectively, and the low potential of 1.35 V to achieve a current density of 100 mA cm−2 for urea oxidation reaction (UOR). Theoretical calculations show that the construction of amorphous/crystalline heterostructure can accelerate the charge transfer between the active site and intermediate, thus enhance the intermediates adsorption and reduce the kinetic barrier toward HER/OER process for enhancing electrocatalytic activity. Importantly, the in-situ Raman spectroscopy discloses that the rapid formation of oxidation-state transition metal oxyhydroxide species would provide more active sites for the oxidation reaction. This multiple electrocatalysis demonstrates the great potential of amorphous/crystalline heterogeneous interfaces for high-performing electrocatalytic conversions.