The synthesis of high-performance catalysts for volatile organic compounds (VOCs) degradation under humid conditions is essential for their practical industrial application. Herein, a codoping strategy was adopted to synthesize the N-Co₃O₄-C catalyst with N, C codoping for low-temperature ethyl acetate (EA) degradation under humid conditions. Results showed that N-Co₃O₄-C exhibited great catalytic activity (T ₉₀ = 177 °C) and water resistance (5.0 vol% H₂O, T ₉₀ = 178 °C) for EA degradation. Characterization results suggested that the C, N codoping weakened the Co-O bond strength, increased surface Co³⁺ and O_ads species, and improved the low-temperature redox ability and the mobility of lattice oxygen species, which boosted the catalytic performance of N-Co₃O₄-C for EA degradation. Meanwhile, the N-doping-induced oxygen vacancies could interact with water vapor to generate extra active oxygen species, which enhanced the water resistance. Importantly, based on a series of characterization technologies, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and theoretical calculations, the synergistic effect of C, N codoping was systematically investigated and elucidated. The C doping induced the increase of surface area and the weakening of Co-O bond strength, which improved EA adsorption and lattice oxygen species activation to dissociate and oxidize EA, forming the key intermediate, acetate acid. N doping enhanced the adsorption and activation of gaseous oxygen species to form active oxygen species, attacking and breaking the C-C bond in acetate acid to accelerate EA deep oxidation, which synergistically facilitated EA degradation.

Photocatalytic reduction of CO₂ to value-added chemicals is a promising technology for reducing atmospheric CO₂, but selectively producing a specific product still remains a great challenge. In this study, a Z-scheme heterojunction, N-doped HTiNbO₅/NH₂-UiO-66(Zr) (referred to as NH-NU), is developed to integrate the advantages of semiconductor photocatalysts and porous CO₂ adsorbents for CO₂-to-CH₄ conversion. The NH-NU Z-scheme heterojunctions are fabricated via a simple one-pot solvothermal method, enabling the formation of a tight and uniform interface between the two phases, thereby facilitating the separation and transfer of the photoinduced charge carriers, as confirmed by TEM, EPR, electrochemical studies, and work functions. As a result, the as-prepared photocatalyst demonstrates a significant increase in selectivity for CH₄ production through CO₂ photoreduction, achieving a 10-fold enhancement compared to that of the pristine MOF, NH₂-UiO-66. Moreover, there is no obvious decrease in the photocatalytic activity for CH₄ production across four consecutive cycles. In situ FT-IR spectroscopy and DFT calculations reveal that charge-enriched N-doped NH-NU-3 composites stabilize various C₁ intermediates in multistep elementary reactions, leading to superior selectivity in the CO₂-to-CH₄ conversion process. This work establishes that efficient and selective heterogeneous catalytic processes can be achieved through the stabilization of reaction intermediates by designing suitable Z-scheme heterojunctions.