Highly Active and Robust Electrocatalyst Based on Nickel Phosphide Supported by Borophene for Oxygen Evolution Reaction

In recent years, transition-metal phosphides (TMPs) have been widely reported as a new candidate as electrocatalysts for electrochemical water splitting. However, the agglomeration of metal phosphide nanoparticles hinders the overall kinetics and stability of such materials. On the other hand, it has already recently been revealed that 2D borophene nanosheets can act as chemical stabilizers for anchoring nanoparticles on their surface, boosting charge transfer during oxygen evolution reaction (OER). Therefore, here, borophene nanosheets are proposed to act as a host of Ni2P nanoparticles. The chemical composition of the prepared material has been investigated, and the influence of the borophene-to-nickel phosphide ratio on the electrochemical properties was tested (B:Ni2P = 1:1, 100:1, 10:1, 1:100, respectively). Interestingly, in the composite of borophene_Ni2P_1:1, the superior electrocatalytic response was observed, with an overpotential equal to 299 mV, a Tafel slope of 53.6 mV/dec, and high durability indicating its promising practical applications as an effective replacement for a commercially used electrocatalyst. What is more, a detailed ex situ study allowed us to demonstrate the mechanism of the boosted OER in the presence of borophene_Ni2P_1:1, indicating the reaction active species and its intermediates. Consequently, the strategy involving the deposition of Ni2P nanoparticles on various 2D materials such as graphene and MoS2 has been employed to demonstrate the viability of this strategy as a universal approach for enhancing electrocatalytic activity. Nonetheless, the findings prove that borophene exhibits superior performance in promoting the electroactivity of guest nanoparticles.