Graphene aerogel-based NiAl-LDH/g-C3N4 with ultratight sheet-sheet heterojunction for excellent visible-light photocatalytic activity of CO2 reduction

NiAl-LDH (NALDH) nanosheets were in intimate contact with g-C3N4 (CN) nanosheets to form ultratight sheet-sheet heterojunctions, which interweaved into network framework with introduction of the graphene aerogel (GA). Notably, the NALDH/CN/GA-20 showed a remarkable CO production rate of 28.83 μmol·g−1·h−1 under visible light irradiation, which was 24 and 16 times those of pure NALDH and bare CN, respectively. Furthermore, it was far exceeding the reported conventional CO2 photocatalytic reduction efficiency. The ultratight sheet-sheet heterojunctions not only shorten the charge transmission distance, but result abundant active sites and coupling large interfaces. The unique structure promoted the transport and separation of photogenerated carriers, and facilitated effective mass transport and light absorption. Multi electron series reduction mechanism based on type-II photocatalytic system was proposed to explain the CO2 reduction pathway. This work provides insight for designing photocatalysts with ideal performance for CO2 reduction.