Artificial photoreduction of CO₂ to clean energy utilizing the unlimited solar energy has shown promise to suppress the greenhouse effect and alleviate the energy shortage. In this study, a simple one-step calcination method was utilized to synthesize ultrathin nanosheet g-C₃N₄ (NS-g-C₃N₄). The prepared NS-g-C₃N₄ with a thickness of 10 nm was demonstrated to exhibited higher efficiency and selectivity than that of bulk counterpart (B-g-C₃N₄) for the photocatalytic reduction of CO₂ to CO under visible light irradiation. The yield of CO in the system with obtained NS-g-C₃N₄ was 5.8 times higher than that of B-g-C₃N₄. CO was measured to be the sole product detected in the system with NS-g-C₃N₄, while CO₂ can be reduced into CO, CH₄ and CH₃OH in the system with B-g-C₃N₄ under the same photocatalytic reduction conditions. The ultrathin nanostructures and abundant surface defect sites of NS-g-C₃N₄ could enhance the visible light adsorption efficiency, favor the separation and transfer of photogenerated carriers, and provide strong chemisorption sites for CO₂, and thus resulting in its remarkable photocatalytic activity to CO₂ reduction. More importantly, the surface defects of nanosheet could shift the adsorption mode of CO₂ from N-CO₂^- for the B-g-C₃N₄ to N-O-C=O for NS-g-C₃N₄, and eventually contributing the selective photoreduction of CO₂ to CO. The obtained also NS-g-C₃N₄ exhibited excellent stability for CO₂ photoreduction. No significant change in the photoreduction efficiency of CO₂ in the system with NS-g-C₃N₄ was observed after four cycles. This study could not only provide a novel strategy to realize the high selectivity and efficiency photocatalytic conversion CO₂ to CO, but also aims to clarify the interactions between the adsorption model of CO₂ on g-C₃N₄ surface and the selectivity and efficiency of CO₂ photoreduction.

利用无限的太阳能对清洁能源进行人工光催化还原CO ₂已显示出有望抑制温室效应并缓解能源短缺的希望。在这项研究中，一种简单的一步煅烧方法被用于合成超薄纳米片gC ₃ N ₄（NS-gC ₃ N ₄）。已证明，所制备的厚度为10 nm的NS-gC ₃ N ₄与可见光照射下将CO ₂光催化还原成CO的效率和选择性比本体的BgC ₃ N ₄更高。获得NS-gC的系统中的CO收率₃ N ₄是BgC ₃ N _4的5.8倍。在NS-gC ₃ N ₄的体系中，CO被测为唯一的产物，而在相同的光催化还原条件下，在BgC ₃ N ₄的体系中，CO ₂可以还原为CO，CH ₄和CH ₃ OH 。NS-gC ₃ N ₄的超薄纳米结构和丰富的表面缺陷位点可以提高可见光的吸附效率，有利于光生载流子的分离和转移，并为CO ₂提供强大的化学吸附位点，因此导致其对CO ₂还原具有显着的光催化活性。更重要的是，纳米片的表面缺陷可能会改变CO的吸附模式₂选自N-CO ₂ ^-为BGC ₃ Ñ ₄至NOC = O为NS-GC ₃ Ñ ₄，并最终促进CO的选择性光还原₂至同样，所得的NS-gC ₃ N ₄对CO _2的光还原表现出优异的稳定性。在使用NS-gC ₃ N ₄的系统中，CO ₂的光还原效率没有明显变化在四个周期后观察到。该研究不仅可以为实现高选择性和高效率的光催化转化CO ₂向CO提供新的策略，而且旨在阐明CO ₂在gC ₃ N ₄表面的吸附模型与CO的选择性和效率之间的相互作用。_2光还原。