Cryptomelane nanowires for highly selective self-heating photothermal synergistic catalytic oxidation of gaseous ammonia

Photothermal selective catalytic oxidation of NH3 (NH3-SCO) provided a cost-effective approach to controling NH3 pollution. However, the contribution of photocatalysis and thermalcatalysis in photothermal NH3-SCO, as well as the synergistic mechanism was not well addressed. Herein, the cryptomelane nanowires were developed for self-heating photothermal NH3-SCO, and excellent NH3 conversion (91.7%) and N2 selectivity (94.7%) were achieved. Furthermore, the study of the synergistic mechanism showed that the photothermal NH3-SCO can be attributed to the thermal-assisted photocatalytic mechanism, which is the synergy of photocatalysis and photothermal effect. Moreover, the reaction paths of photothermal and thermal NH3-SCO were comparative studied. For the photothermal NH3-SCO, it is considered to follow the photo-iSCR mechanism, in which the activation of NH3 into •NH2 by photogenerated holes serves a key role; while the thermalcatalysis is mainly dominated by the iSCR mechanism and supplemented by the imide mechanism. This research provides fundamental insights into the photothermal NH3-SCO mechanism.