Topological materials are promising electrocatalysts for the hydrogen evolution reaction (HER) because of their protected electronic states and exceptional carrier mobility. Among them, the topological metal Pt3Te4 (mitrofanovite) exhibits low Tafel slopes in the nanocrystals. Realizing this potential in scalable catalyst systems requires nanoscale texturing coupled with precise control of the surface chemistry under operating conditions. Herein, we demonstrate that hydrogen peroxide (H2O2)-assisted liquid-phase exfoliation (LPE) of bulk Pt3Te4 yields nanoporous nanosheets that retain their metallic character and are chemically preconditioned to develop a bias-controlled PtO2 skin that governs the catalytic activity. Crucially, spectromicroscopy resolves termination-selective oxidation: PtO2 forms exclusively on PtTe2-like terminations, whereas Pt2Te2 terminations remain metallic. Operando ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) in an electrochemical cell revealed the bias-dependent emergence of surface oxide phases in H2O2-treated nanosheets. The joint effect of the higher accessible site density imparted by nanoporosity and the emergence of a bias-controlled PtO2/PtTe2-terminated Pt3Te4 surface junction rationalizes the improved catalytic activity: the overpotential at 10 mA cm-2 decreases by similar to 30% (from 113.1 to 78.7 mV), while the exchange current density more than triples (from 0.106 to 0.347 mA cm-2), all with an unchanged Tafel slope (similar to 53 mV dec-1) and sustained stability over 50 h in acid. By combining a single scalable top-down step with operando proof that the catalytically active oxide is switched on by bias rather than being a static passivation layer, this study establishes a precise interface-engineering principle for Pt3Te4 nanosheets and a practical path to efficient, scalable HER catalysts based on nanosheets of topological metals.
Scalable Defect Engineering of Pt3Te4Nanosheets Activates an Electro-Switchable and Termination-Dependent PtO2Skin for Low-Overpotential Hydrogen Evolution
Cupolillo A.
Supervision
;
2026-01-01
Abstract
Topological materials are promising electrocatalysts for the hydrogen evolution reaction (HER) because of their protected electronic states and exceptional carrier mobility. Among them, the topological metal Pt3Te4 (mitrofanovite) exhibits low Tafel slopes in the nanocrystals. Realizing this potential in scalable catalyst systems requires nanoscale texturing coupled with precise control of the surface chemistry under operating conditions. Herein, we demonstrate that hydrogen peroxide (H2O2)-assisted liquid-phase exfoliation (LPE) of bulk Pt3Te4 yields nanoporous nanosheets that retain their metallic character and are chemically preconditioned to develop a bias-controlled PtO2 skin that governs the catalytic activity. Crucially, spectromicroscopy resolves termination-selective oxidation: PtO2 forms exclusively on PtTe2-like terminations, whereas Pt2Te2 terminations remain metallic. Operando ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) in an electrochemical cell revealed the bias-dependent emergence of surface oxide phases in H2O2-treated nanosheets. The joint effect of the higher accessible site density imparted by nanoporosity and the emergence of a bias-controlled PtO2/PtTe2-terminated Pt3Te4 surface junction rationalizes the improved catalytic activity: the overpotential at 10 mA cm-2 decreases by similar to 30% (from 113.1 to 78.7 mV), while the exchange current density more than triples (from 0.106 to 0.347 mA cm-2), all with an unchanged Tafel slope (similar to 53 mV dec-1) and sustained stability over 50 h in acid. By combining a single scalable top-down step with operando proof that the catalytically active oxide is switched on by bias rather than being a static passivation layer, this study establishes a precise interface-engineering principle for Pt3Te4 nanosheets and a practical path to efficient, scalable HER catalysts based on nanosheets of topological metals.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
