Single‐atom catalysts (SACs) attract extensive attention in the field of heterogeneous catalysis in recent years due to the maximum atom utilization and unique physical and chemical properties. The gas sensing is actually a heterogeneous catalysis process but the SACs are new to this area. Although SACs show huge potential in gas sensing, the SACs gas sensing area currently is still at the infancy stage. This work critically reviews the recent advances and current status of single‐atom gas sensing materials. General synthesis routes, characterization methods, and sensing performance indexes are introduced. At the end, the challenges and future prospects on SACs gas sensing are presented from the authors’ perspectives. This work is anticipated to provide insights and guideline for the chemical sensing community.

2D transition metal carbides/nitrides (MXenes) are thought of promising photothermal materials due to their broadband localized surface plasma resonance (LSPR) and attractive electromagnetic interference (EMI) properties. However, the weak oxidation resistance and unclear photothermal mechanism of MXenes impede their photothermal modulations. Herein, the in‐plane 2D Ti3C2/TiO2 heterostructures are fabricated by partial oxidation and an unconventional photothermal effect under near infrared irradiation, even if the oxidation compromises the EMI and LSPR capacities, is demonstrated. Such performance is ascribed to the faster transfer of photoexcited electrons across the seamless in‐plane Ti3C2/TiO2 heterointerface than the reported out‐of‐plane one, and the 1–2 orders of magnitude faster relaxation processes of electrons than the ground bleaching in the Original MXene. These experimental results are well‐supported by theoretical calculations. The conceptual advances broaden the fundamental understanding of the photoconversion of MXenes, which would be extended into a variety of applications, such as biomedical therapy, photosynthesis, and photovoltaics.

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