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 (H2 O2 ). 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 Ni2+ with different amounts of BH4 - . Among borides, the amorphous NiB2 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 H2 O2 production rate of 4.753 mol gcat -1 h-1 is achieved upon assembling NiB2 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 OO bond.
Keywords: amorphous phase; charge transfer; electronic structure; hydrogen peroxide; oxygen reduction reaction.
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