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To avoid carcinogenicity, formaldehyde gas, currently being only detected at higher operating temperatures, should be selectively detected in time with ppb concentration sensitivity in a room-temperature indoor environment. This is achieved in this work through introducing oxygen vacancies and Pt clusters on the surface of In2O3 to reduce the optimal operating temperature from 120 to 40 °C. Previous studies have shown that only water participates in the competitive adsorption on the sensor surface. Here, we experimentally confirm that the adsorbed water on the fabricated sensor surface is consumed via a chemical reaction due to the strong interaction between the oxygen vacancies and Pt clusters. Therefore, the long-term stability of formaldehyde gas detection is improved. The results of theoretical calculations in this work reveal that the excellent formaldehyde gas detection of Pt/In2O3–x originates from the electron enrichment due to the surface oxygen vacancies and the molecular adsorption and activation ability of Pt clusters on the surface. The developed Pt/In2O3–x sensor has potential use in the ultraefficient, low-temperature, highly sensitive, and stable detection of indoor formaldehyde at an operating temperature as low as room temperature.

Solar-driven interface evaporation recently emerges as one of the most promising methods for seawater desalination and wastewater purification, mainly due to its low energy consumption. However, there still exist special issues in the present material system based on conventional noble metals or two-dimensional (2D) nanomaterials etc., such as high costs, low light-to-heat conversion efficiencies, and unideal channels for water transport. Herein, a composite photothermal membrane based on Ti 3 C 2 T x MXene nanoflakes/copper indium selenide (CIS) nanoparticles is reported for highly efficient solar-driven interface evaporation toward water treatment applications. Results indicate that the introduction of CIS improves the spatial accessibility of the membrane by increasing the interlayer spacings and wettability of MXene nanoflakes and enhances light absorption capability as well as reduces reflection for the photothermal membrane. Simultaneously, utilization of the MXene/CIS composite membrane improves the efficiency of light-to-heat conversion probably due to formation of a Schottky junction between MXene and CIS. The highest water evaporation rate of 1.434 kgm −2 h −1 and a maximum water evaporation efficiency of 90.04% as well as a considerable costeffectiveness of 62.35 g h −1 /$ are achieved by using the MXene/CIS composite membrane for solar interface evaporation, which also exhibits excellent durability and light intensity adaptability. In addition, the composite photothermal membrane shows excellent impurity removal ability, e.g., >98% for salt ions, >99.8% for heavy metal ions, and ∼100% for dyes molecules. This work paves a promising avenue for the practical application of MXene in the field of water treatment.

La3+-Doped ZnWO4 nanorods were prepared via a hydrothermal method for the photocatalytic NO removal under simulated solar light irradiation.

Plasmonic bismuth (Bi 0) nanoparticle-decorated flower-like CeO 2−δ (Bi 0 /CeO 2−δ) photocatalysts with abundant oxygen vacancies (OVs) were synthesized via a solvothermal method. The OVs can not only improve the separation of electron-hole pairs, but also facilitate the adsorption and activation of gas molecules (NO/O 2). In addition, the Bi 0 nanoparticles can enhance the visible light response and prevent the recombination of charge carriers by virtue of the surface plasmon resonance (SPR) effect, achieving an excellent ability for NO elimination and NO 2 inhibition under visible light irradiation. Density functional theory (DFT) calculations confirm that the Schottky barrier between Bi 0 and CeO 2−δ accompanied with the OVs are pivotal for the migration of photogenerated charge carriers to involve in the photocatalytic NO removal. Trapping experiments and in situ FTIR spectroscopy were conducted to explore the mechanism of the photocatalytic NO removal, suggesting that the photocatalytic NO removal can be significantly enhanced by introducing abundant OVs and the involvement of Bi 0 metal nanoparticles.

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