POM-Based Water Splitting Catalyst Under Acid Conditions Driven by Its Assembly on Carbon Nanotubes.
basic_science · Level V
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- Record sourced from PubMed, PMID 41294174.
- Also identified by DOI 10.1002/adma.202512902.
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Abstract
Development of efficient and stable bifunctional electrocatalysts for water electrolysis under acidic conditions is essential for sustainable hydrogen production. A novel vanadium polyoxometalate (POM)-based material, Na<sub>4</sub>(H<sub>2</sub>O)<sub>12</sub>[(CH<sub>2</sub>OH)<sub>3</sub>CNH<sub>3</sub>]<sub>2</sub>[V<sub>10</sub>O<sub>28</sub>]·4H<sub>2</sub>O (1) is presented, incorporating non-innocent cations and whose electrocatalytic activity can be switched from the production of oxygen to hydrogen through its assembly on carbon nanotubes (CNT). A physical mixture (1/CNT) shows remarkable oxygen evolution reaction (OER) activity, with an overpotential of 0.34 V at 10 mA cm<sup>-</sup> <sup>2</sup>, outperforming commercial IrO<sub>2</sub> (0.45 V) and approaching Ir/C (0.31 V), with 80% Faradaic efficiency. In contrast, directed assembly (1@CNT) unlocks TRIS ⁺= [(CH<sub>2</sub>OH)<sub>3</sub>CNH<sub>3</sub>]⁺ groups functionality, enabling high hydrogen evolution reaction (HER) efficiency, with an onset potential of -0.07 V, close to Pt/C, and 94% Faradaic efficiency. Mechanistic studies, strongly supported by in-operando confocal microscopy and theoretical calculations, reveal that the modulation of crystal interactions and the local microenvironment is key to orchestrating the OER/HER tuning. OER is proposed to proceed via an alcohol oxidation reaction (AOR), while HER benefits from TRIS⁺ moieties acting as a "proton sponge". This work provides a compelling approach for rational design of bifunctional molecular electrocatalysts based on earth-abundant elements and controlled nanoassembly, with clear relevance for advancing green hydrogen production technologies.