Manipulation of Oxidation States on Phase Boundary via Surface Layer Modification for Enhanced Alkaline Hydrogen Electrocatalysis.
basic_science · Level V
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- Record sourced from PubMed, PMID 39072907.
- Also identified by DOI 10.1002/adma.202405128.
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Abstract
In alkaline water electrolysis and anion exchange membrane water electrolysis technologies, the hydrogen evolution reaction (HER) at the cathode is significantly constrained by a high energy barrier during the water dissociation step. This study employs a phase engineering strategy to construct heterostructures composed of crystalline Ni<sub>4</sub>W and amorphous WO<sub>x</sub> aiming to enhance catalytic performance in the HER under alkaline conditions. This work systematically modulates the oxidation states of W within the amorphous WO<sub>x</sub> of the heterostructure to adjust the electronic states of the phase boundary, the energy barriers associated with the water dissociation step, and the adsorption/desorption properties of intermediates during the alkaline HER process. The optimized catalyst, Ni<sub>4</sub>W/WO<sub>x</sub>-2, with a quasi-metallic state of W coordinated by a low oxygen content in amorphous WO<sub>x</sub>, demonstrates exceptional catalytic performance (22 mV@10 mA cm<sup>-2</sup>), outperforming commercial Pt/C (30 mV@10 mA cm<sup>-2</sup>). Furthermore, the operando X-ray absorption spectroscopy analysis and theoretical calculations reveal that the optimized W atoms in amorphous WO<sub>x</sub> serve as active sites for water dissociation and the nearby Ni atoms in crystalline Ni<sub>4</sub>W facilitated the release of H<sub>2</sub>. These findings provide valuable insights into designing efficient heterostructured materials for energy conversion.