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 CO 2 photocatalytic reduction over graphitic carbon nitride (g-C 3 N 4 ). It was surprisingly found that thiourea derived g-C 3 N 4 (TCN), which showed inferior activity in CO 2 reduction under visible light irradiation, exhibited more remarkable CO 2 conversion efficiency under >200   nm light irradiation compared to g-C 3 N 4 synthesized from urea (UCN) and commercial TiO 2 (P25). Also, the highest selectivity to CO 2 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 –NH x species that were responsible for CO 2 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 CO 2 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.