Hierarchical Morphology Engineering of Silicon Micropillars Dictates Interfacial Kinetics for Room-Temperature Hydrogen Sensing

However, traditional top-down microfabrication typically yields inherently smooth sidewalls, restricting active site density and causing the “premature saturation” of interfacial reactions. Herein, we report a controllable morphology engineering strategy via one-step metal-assisted chemical etching (MACE) to fabricate hierarchical silicon micropillars (HMPs) with in situ sculpted nanoscale rough sidewalls.

To elucidate the impact of this hierarchical morphology on interfacial kinetics, we employed Pd-modified HMPs for room-temperature H₂ sensing as a proof-of-concept model. This custom architecture effectively bypasses the morphological bottlenecks of traditional smooth micropillars (SMPs). The optimized Pd/HMPs sensor achieved a response of up to 628% toward 1% H₂a > 6-fold enhancement over its SMPs counterpartwith a low detection limit of 200 ppb.