Dynamic Self‐Switching Electronic State of Pt Sites for Boosting Bifunctional Hydrogen Electrocatalysis and Low‐Temperature Energy Conversion

Why It Matters

Dynamic electronic tuning overcomes the static‑structure limitation of conventional bifunctional catalysts, enabling high‑efficiency hydrogen conversion even at sub‑zero temperatures.

Key Takeaways

• Proton insertion converts WO3 to metallic HxWO3.
• Electron-rich Pt reduces HER barrier to 0.327 eV.
• Electron-deficient Pt cuts HOR barrier to 0.325 eV.
• HER overpotential 56 mV at 100 mA cm⁻².
• Battery delivers 170 mAh g⁻¹, 80 mAh g⁻¹ at –40 °C.

Pulse Analysis

The persistent bottleneck in hydrogen‑fuel technologies is finding a single electrocatalyst that excels at both the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR). Traditional catalysts possess fixed electronic structures, forcing a compromise between activity and stability for the two opposing processes. The Pt/WO3 system breaks this paradigm by embedding Pt on a tungsten oxide support that can reversibly intercalate protons, turning a semiconducting oxide into a metallic‑like HxWO3 phase. This structural fluidity grants the catalyst a self‑adjusting electronic environment, a concept that aligns with emerging trends in adaptive materials for energy conversion.

During HER, a negative bias drives H⁺ into the WO3 lattice, forming HxWO3 and donating electrons to adjacent Pt atoms. The resulting electron‑rich Pt surface weakens the hydrogen adsorption energy, slashing the calculated activation barrier from 0.439 eV to 0.327 eV. Conversely, under HOR conditions, a positive bias extracts protons, reverting HxWO3 to pristine WO3 and restoring an electron‑deficient Pt state that optimally binds hydrogen for oxidation, reducing the barrier to 0.325 eV. These mechanistic shifts translate into practical metrics: a mere 56 mV overpotential at 100 mA cm⁻² for HER and a record‑high HOR exchange current density of 5.8 mA cm⁻².

The broader implication is a viable route to high‑performance protonic hydrogen batteries (HPBs) that operate efficiently across a wide temperature range. The Pt/WO3 anode sustains a discharge capacity of 169.9 mAh g⁻¹ at modest current densities and retains 80 mAh g⁻¹ even at –40 °C, addressing a critical hurdle for off‑grid and cold‑climate applications. By demonstrating that catalyst electronic states can be actively modulated in situ, this work opens pathways for next‑generation bifunctional electrocatalysts, potentially accelerating the commercialization of hydrogen‑based power and storage solutions.