From Solvent Choice to Catalytic Performance: Redefining the Washing Step for Hydroxyl-Mediated Architecture Engineering

This work redefines the washing step in conventional precipitation synthesis, elevating it from a routine purification procedure to a decisive handle for engineering the microstructure of heterogeneous catalysts. Beyond merely preserving texture, we find that replacing water with ethanol induces a critical chemical effect: it selectively stabilizes hydroxyl groups in the zirconium hydroxide precipitate. This modification initiates a deterministic structural evolution: it directs the formation of phase-pure monoclinic ZrO2 upon calcination, which subsequently templates the assembly of supported PdO nanoparticles enriched with active edge/step sites at twin boundaries. The resulting architecture─arising from this tailored precursor chemistry─simultaneously enhances C–H activation and water tolerance, endowing Pd/ZrO2 with exceptional low-temperature activity and sustained durability for methane oxidation. The generality of this approach, rooted in hydroxyl-chemistry control, is demonstrated by its successful extension to CeO2 and TiO2 supports, where ethanol washing similarly refines the microstructure and enriches PdO edge/step sites, thereby boosting methane oxidation activity. Its broad applicability is further validated by the consistently superior CO oxidation performance across all ethanol-washed catalysts. Consequently, our work establishes a general design paradigm wherein solvent selection during post-precipitation washing serves as a primary, chemical, scalable lever for the precise construction of high-performance catalytic architectures.