Cobalt carbide nanosheets as effective catalysts toward photothermal degradation of mustard-gas simulants under solar light

Here, ultrathin cobalt carbide (Co2C) nanosheets are firstly illustrated as effective and robust catalysts toward photothermal degradation of sulfur mustard simulants (e.g., 2-chloroethyl ethyl sulfide, CEES) under solar light. Under the optimal conditions, the degradation rate of CEES by Co2C nanosheets is up to 98 %, which is much higher than the widely used P25 and anatase TiO2 nanoparticles. Moreover, the degradation performance is comparable or even better than those typical photothermal catalysts, including MnO2, MnOx-TiO2 and Co3O4, under identical conditions. Experimental evidences and density functional theory (DFT) calculations reveal that the superior activity is attributed to three main reasons: (i) the high photo-to-heat conversion efficiency of Co2C enables an elevated surface temperature for chemical bond breaking, (ii) the feasible binding of CEES on Co2C surface via Co–S and Co–Cl coordination promotes the process of degradation, and (iii) the surface hydroxyl groups (–OH) on Co2C nanosheets favor the degradation of CEES. Obviously, this work provides new insights into practical and large-scale application of transition metal carbides (TMCs) as novel photothermal catalysts in the decontamination of chemical warfare agents (CWAs) under ambient conditions (i.e., solar light and room temperature).