Band engineering of non-metal modified polymeric carbon nitride with broad spectral response for enhancing photocatalytic CO2 reduction

[Display omitted] •The novel Bro-PCN nanosheets were prepared under a unique synthetic method.•The electronic structure redistribution promotes the migration of carriers.•The prepared 0.3 Bro-PCN displays boosted CO2 photoreduction performance.•The reaction mechanisms were revealed by in situ FTIR and DFT calculation. The development of environmentally friendly, low-cost, and efficient catalysts is crucial for photocatalytic CO2 conversion, and polymeric carbon nitride (PCN) is a promising star material for balancing carbon transformation. However, the application of PCN in the field of photocatalytic CO2 reduction is limited by the narrow photoresponse range and slow carrier separation behavior. In this work, a co-polymerization strategy of glycolic acid and urea was adopted to construct a Brown PCN (Bro-PCN) with a Broad spectral response while realizing the introduction of oxygen element which can promote the reconstruction of the electronic structure. The result shows that the Bro-PCN exhibits excellent CO generation performance compared with pristine PCN, even in the spectral range greater than 700 nm, showing the ability to promote the conversion of CO2 to CO. Experimental characterizations and DFT calculation confirmed that the excellent photocatalytic CO2 conversion ability is attributed to the improvement of light absorption and the contribution of added sub-gap impurity states to charge separation behavior and active sites. Thus, this work offers a universal strategy and insights into the design of broad spectral responsive PCN materials in the field of photocatalytic CO2 reduction.