Composition Engineering of Amorphous Nickel Boride Nanoarchitectures Enabling Highly Efficient Electrosynthesis of Hydrogen Peroxide.

Developing advanced electrocatalysts with exceptional two electron (2e ^- ) selectivity, activity, and stability is crucial for driving the oxygen reduction reaction (ORR) to produce hydrogen peroxide (H ₂ O ₂ ). Herein, a composition engineering strategy is proposed to flexibly regulate the intrinsic activity of amorphous nickel boride nanoarchitectures for efficient 2e ^- ORR by oriented reduction of Ni ²⁺ with different amounts of BH ₄ ^- . Among borides, the amorphous NiB ₂ delivers the 2e ^- selectivity close to 99% at 0.4 V and over 93% in a wide potential range, together with a negligible activity decay under prolonged time. Notably, an ultrahigh H ₂ O ₂ production rate of 4.753 mol g _cat ^-1 h ^-1 is achieved upon assembling NiB ₂ in the practical gas diffusion electrode. The combination of X-ray absorption and in situ Raman spectroscopy, as well as transient photovoltage measurements with density functional theory, unequivocally reveal that the atomic ratio between Ni and B induces the local electronic structure diversity, allowing optimization of the adsorption energy of Ni toward *OOH and reducing of the interfacial charge-transfer kinetics to preserve the OO bond.
(© 2022 The Authors. Advanced Materials published by Wiley-VCH GmbH.)