Photocatalytic carbon dioxide (CO2) reduction technology is considered a promising approach to alleviate greenhouse gas emissions in the earth's atmosphere. Carbon dots (CDs), which possess good optical properties, are of keen interest in the field of photocatalysis. Iron (Fe), a transition metal element with vacant 3d orbital that contributes to the electron‐transfer process, is a promising metal dopant for CDs that allows for the preparation of multifunctional CDs. Fe‐doped carbon dots (Fe−CDs) were synthesized using ethylenediamine tetraacetic acid disodium (EDTA‐2Na) and ferric chloride (FeCl3 ⋅ 6H2O) through a simple one‐step hydrothermal method. The chemical structure of the obtained Fe−CDs was studied, and their activity for the photocatalytic reduction of CO2 was tested. The results show that Fe doping amount of 13.0 wt.% is the most favorable for the photocatalytic reaction. The maximum photocatalytic reduction of CO2 to methanol reaches 654.28 μmol ⋅ g−1 ⋅ h−1 within 6 h, which is about 2.6 times of the methanol yield of CDs, which is attributed to high electron transfer rate of Fe dopant.

The global energy shortage and environmental degradation are two major issues of concern in today’s society. The production of renewable energy and the treatment of pollutants are currently the mainstream research directions in the field of photocatalysis. In addition, over the last decade or so, graphene (GR) has been widely used in photocatalysis due to its unique physical and chemical properties, such as its large light-absorption range, high adsorption capacity, large specific surface area, and excellent electronic conductivity. Here, we first introduce the unique properties of graphene, such as its high specific surface area, chemical stability, etc. Then, the basic principles of photocatalytic hydrolysis, pollutant degradation, and the photocatalytic reduction of CO2 are summarized. We then give an overview of the optimization strategies for graphene-based photocatalysis and the latest advances in its application. Finally, we present challenges and perspectives for graphene-based applications in this field in light of recent developments.

Developing superior photocatalytic CO2 conversion systems for the generation of high-valued fuels or chemicals is highly desirable but is still challenging work. Herein, the well-organized carbon nitride/Zn-doped bismuth vanadium oxide (CN-ZnBVO) nanohybrids were constructed by a facile CTAB-assisted solvothermal strategy to achieve an efficient photocatalytic reduction of CO2 to CH3OH under UV–vis light. Impressively, the distinctive butterfly-like 2D/2D CN-ZnBVO catalyst showed markedly enhanced photocatalytic performance in alkaline medium, with the largest CH3OH generation rate of 609.1 μmol g–1 h–1 and a high selectivity of 90.5%, outperforming most recently reported CO2 photoreduction systems. Moreover, the yield of CH3OH remained nearly constant over three successive repeated cycles, signifying its good stability. Detailed characterization and theoretical calculations revealed that the outstanding photocatalytic activity owes much to the more accessible reaction sites and improved CO2 absorption capacity induced by the distinctive micromorphology effect, as well as the localized charge density distribution and fast spatial charge separation and transfer caused by the 2D/2D S-scheme heterojunction, thus providing more photogenerated electrons for efficient CH3OH formation. The present work offers a new perspective for the in situ construction of highly active S-scheme heterostructures for selective photocatalytic CO2 reduction.