A Fractal-Tip Cu<sub>3</sub>Ni/NiMoO<sub>4</sub> Heterostructure for Efficient Hydrogen Evolution via an Accelerated Volmer-Tafel Mechanism.
basic_science · Level V
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- Record sourced from PubMed, PMID 41020781.
- Also identified by DOI 10.1021/acsnano.5c11278.
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Abstract
Achieving hydrogen evolution at industrial current densities requires optimized kinetics involving electron transfer, catalytic reactions, and mass transport. Here we report a Cu<sub>3</sub>Ni alloy and amorphous NiMoO<sub>4</sub> heterostructure featuring a Romanesco-like fractal-tip architecture grown on a copper mesh. This cathode exhibits outstanding catalytic activity, requiring low overpotentials of 144.0 and 122.5 mV to reach 1 A cm<sup>-2</sup> in 1 M KOH and 100 mA cm<sup>-2</sup> in 1 M PBS, respectively, along with a Tafel slope as low as 27.2 mV dec<sup>-1</sup> in alkaline media. It also maintains long-term durability over 3000 h at 1 A cm<sup>-2</sup> with negligible degradation. At the Cu<sub>3</sub>Ni/NiMoO<sub>4</sub> interface, the distinct chemical environments of Ni atoms result in hydrogen affinity in Cu<sub>3</sub>Ni and oxygen affinity in NiMoO<sub>4</sub>, promoting water dissociation (H*-*OH). Experimental results and theoretical calculations reveal that the interface lowers the energy barrier for water dissociation and increases H* coverage, shifting the reaction mechanism from the Volmer-Heyrovsky pathway to the more efficient Volmer-Tafel route. Furthermore, the fractal-tip structure boosts HER kinetics by amplifying local electric fields, concentrating protons, and accelerating bubble release. This work provides a rational design strategy for improving hydrogen evolution kinetics through combined structural and interfacial optimization.