Regulating the electronic structure of Ir single atoms by ZrO₂ nanoparticles for enhanced catalytic oxidation of formaldehyde at room temperature

Developing low-loading single-atom catalysts with superior catalytic activity and selectivity in formaldehyde (HCHO) oxidation at room temperature remains challenging. Herein, ZrO₂ nanoparticles coupled low-loading Ir single atoms in N-doped carbon (Ir₁-N-C/ZrO₂) was prepared. The optimal Ir₁-N-C/ZrO₂ with 0.25 wt% Ir loading delivers the high HCHO removal and conversion efficiency (>95%) at 20 °C, which is higher than that over Ir₁-N-C with the same Ir loading. The specific rate can reach 1285.6 mmol g_Ir⁻¹ h⁻¹, surpassing the Ir based catalysts reported to date. Density functional theory calculation results and electron spin resonance spectra indicate that the introduction of ZrO₂ nanoparticles modulate the electronic structure of the Ir single atoms, promoting O₂ activation to ^•O₂^–. Moreover, the Ir-C-Zr channel is favorable for the dissociation of ^•O₂^– to active oxygen atom (*O), and further accelerates the transformation of HCHO and intermediates (dioxymethylene and formates) to CO₂ and H₂O. This work provides a facile strategy to design low-loading single-atom catalysts with high catalytic activity toward HCHO oxidation.