Interfacial Oxygen Vacancy Engineered Two-Dimensional g-C₃N₄/BiOCl Heterostructures with Boosted Photocatalytic Conversion of CO₂

Abstract

The CO 2 conversion by photocatalysis has been a focus of global concern as yet, and the exploring of efficient heterostructures is critical to promote the photocatalytic performance. However, the weak interface contact largely limits the photogenerated carrier transfer and restrains the activities of heterostructures. In this work, two-dimensional (2D) g-C 3 N 4 / BiOCl heterostructures were exemplified to demonstrate a facile strategy of interfacial oxygen vacancies (IOVs) with enhanced interfacial interaction to promote the photocatalytic conversion of CO 2 . Both experimental results and density functional theory calculations determined that the IOVs can provide a transport channel for the interfacial carriers, leading to a built-in electric field from g-C 3 N 4 to BiOCl and a Z-scheme type for IOVs-introduced g-C 3 N 4 /BiOCl heterostructures, which largely promoted the photogenerated carrier transfer efficiency. This further induced the generation of more electrons to participate in the surface reactions and significantly reduced the energy barriers for the CO 2 reduction, especially facilitating the decomposition of intermediate COOH into CO. As a result, the photocatalytic activity of IOVs-introduced g-C 3 N 4 /BiOCl heterostructure for the conversion of CO 2 to CO was enhanced by 1.6 times compared to pristine g-C 3 N 4 /BiOCl. This work could provide insights into the important role of oxygen vacancies in boosting the reduction activity of CO 2 for the heterojunctions and provide a facile route for designing highly efficient 2D heterostructures in the field of photocatalysis.

Vacancy Engineering of Ultrathin 2D Materials for Photocatalytic CO2Reduction

“…Of note, the interfacial interaction in the heterostructure is very vital for charge transfer, which is directly linked to the CO 2 reduction performance. For example, Zhou et al [53] . prepared layered BiOCl nanosheets with rich oxygen vacancies (BOC−O V ) coupled with C 3 N 4 (CN) nanosheets.…”

Engineering approach toward catalyst design for solar photocatalytic CO 2 reduction: A critical review

“…Moreover, surface defect engineering can effectively improve the separation efficiency of photogenerated electron/hole pairs and meanwhile adjust the electronic structure broadening the light absorption range. A great deal of precious works dedicated to engineering surface defect are available here for easy reference 28,31,43,97‐101 . For example, Xia et al 101 unraveled how the surface defects of catalyst work when applied in photocatalytic CO 2 reduction.…”

“…In contrast, converting CO 2 into highly value‐added chemical fuels makes more sense. Thus, scientists have transferred their research focus to artificial conversion of CO 2 and developed some major strategies, including conventional thermochemical, 14‐19 electrochemical, 20‐24 and photocatalytic methods 25‐34 . In the last decade, thermochemical conversion of CO 2 has witnessed a significant progress in both product selectivity and productivity (turnover numbers, TONs).…”

A Mini Review of the Preparation and Photocatalytic Properties of Two-Dimensional Materials

“…In the process of photocatalysis, the construction of heterojunctions by combining two different semiconductors, especially the two-dimensional (2D) layered structure with appropriate conductive potential and valence band potential, is one of the most effective ways to improve the separation efficiency of photogenerated carriers. In addition, two-dimensional (2D) g-C 3 N 4 /BiOCl heterostructures demonstrate a facile strategy of interfacial oxygen vacancies (IOVs) with enhanced interfacial interaction to promote the photocatalytic conversion of CO 2 (Chen Y. et al, 2020 ). Z-Scheme assembly of 2D ZnV 2 O 6 /RGO/g-C 3 N 4 nanosheets with RGO/pCN as solid-state electron mediators enables efficient CO 2 conversion under visible-light irradiation (Bafaqeer et al, 2019 ).…”