Photocatalytic CO2 transformation into fuel: A review on advances in photocatalyst and photoreactor

Over the past years, a serious contemplation has revealed the need to resolve two major complications: global warming due to rising levels of atmospheric carbon dioxide (CO2) and the alarming consumption of energy resources. Solar fuel production from green CO2 gas would be a convenient solution to resolve both problems simultaneously. Various conventional technologies and their limitations over CO2 transformation into fuels are reviewed in this paper. In the main stream, the review categorizes different types of photocatalysts used in previous photocatalytic conversion of CO2 processes (with detailed information regarding operating conditions, catalysts׳ preparation techniques, physical properties of catalysts, radiation sources, and selectivity) based on metal oxides, sulfides, phosphides, p-type and non-metal oxide semiconductors. Also, the catalysts modified by doping co-metals, noble metals, transition metals and non-metals for visible light response have been highlighted. Moreover, the recent prospect and advancement of novel sensitized catalysts by dye elements, phthalocyanines and quantum dots (QDs) for harnessing solar fuels are prominent in this outline. Reviews of this topic have also focused on the progression of photocatalytic reactors especially for CO2 photoreduction. Recently, advanced optical fibers and monolith photochemical reactors have become prominent because of their vast photon-harvesting ability. However, this technology needs more implementation with efficient catalyst selection and the development of giant solar reactors for industrial establishment. The current scenario shows that immense prospects and opportunities still exist in this area, but require further investigation and establishment.