Surprisingly advanced CO2 photocatalytic conversion over thiourea derived g-C3N4 with water vapor while introducing 200-420 nm UV light

200-420 nm UV light was for the first time introduced for CO2 photocatalytic reduction over graphitic carbon nitride (g-C3N4). It was surprisingly found that thiourea derived g-C3N4 (TCN), which showed inferior activity in CO2 reduction under visible light irradiation, exhibited more remarkable CO2 conversion efficiency under > 200 nm light irradiation compared to g-C3N4 synthesized from urea (UCN) and commercial TiO2 (P25). Also, the highest selectivity to CO2 conversion was observed over TCN while P25 showed the most prominent H-2 production followed by UCN. Through a series of characterizations, the more abundant -NHx species that were responsible for CO2 activation, the enhanced reducing ability of photo-excited electrons under UV light and the higher photo-exited electron-hole separation efficiency were supposed to contribute to the excellent CO2 photocatalytic reduction activity of TCN under > 200 nm UV-vis light irradiation, whilst its visible-light activity was relatively weak because of its limited surface area. Further, TCN performed a wonderful stability with a good record of circle tests in this irradiation condition. (C) 2016 Elsevier Ltd. All rights reserved.