Dynamic Thermocatalytic Response of Pd Nanoclusters under Pulse Operation: Toward Self-Calibrating Hydrogen Sensing

Thermocatalytic reactions inherently couple electrical heating, thermal dissipation, and exothermic chemical processes, yet this interplay remains obscured under conventional steady-state operation. Here, we investigate the dynamic thermocatalytic response of Pd nanocluster/Al2O3/Pt planar devices under pulse-driven excitation, which separates subignition and catalytic segments within each cycle. The transient resistance evolution reveals a smooth transition from purely thermal to thermocatalytic regimes, allowing quantitative decoupling of the reaction contribution through a compact power-law model of the hydrogen-insensitive baseline. The extracted gas-induced resistance change (ΔRgas) follows a robust quadratic dependence on hydrogen concentration, with coefficients that systematically evolve with voltage and temperature, confirming that the observed nonlinearity originates from intrinsic thermocatalytic feedback rather than electrical artifacts. This pulse-driven framework not only reproduces steady-state calibration behavior with approximately 78% lower energy consumption but also establishes a general approach for probing and modeling heat–reaction coupling in catalytic sensors, providing mechanistic insight into dynamic thermocatalysis and a pathway toward efficient, drift-resistant hydrogen detection.