Indirect Z-Scheme Assembly of 2D ZnV₂O₆/RGO/g-C₃N₄ Nanosheets with RGO/pCN as Solid-State Electron Mediators toward Visible-Light-Enhanced CO₂ Reduction

Abstract

Indirect Z-scheme assembly of graphene-bridged 2D ZnV2O6/pCN nanosheets composite has been fabricated by one-step solvothermal process and tested for photoinduced CO2 conversion under visible-light irradiations. The highest CH3OH production of 3488 μmol g-cat–1 was obtained over ZnV2O6/RGO/g-C3N4 composite, 1.02 and 1.25 times higher comparing to ZnV2O6/RGO and ZnV2O6/g-C3N4 samples, respectively. This enhanced efficiency can be ascribed to well-designed ternary heterojunction with hierarchical structure and efficient charges separation by RGO. More importantly, CH3OH yield was further improved by introducing RGO/pCN as an electron sink, which led to a 1.07 times higher yield than using only RGO. This reveals that ternary 2D ZnV2O6/RGO/pCN nanostructure has higher visible-light absorption, improved charge separation, and enhanced photocatalytic efficiency due to RGO/pCN as multiple mediators. The stability of composite catalyst also prevailed for 32 h for continuous CH3OH production. Therefore, structured Z-scheme composite with multiple electron mediators enables efficient CO2 conversion under visible-light irradiation.

Nanostructured Carbon Nitrides for CO2 Capture and Conversion

“…could also be hybridized on to the g‐C 3 N 4 as a co‐catalyst to prompt charge‐carrier separation, kinetic transfer and this strategy is conventionally employed for hybrids of C 3 N 4 and semiconductors to enhance the photocatalytic efficiency of the hybrids . Conductive carbons such as graphene and amorphous carbon are also good additives to facilitate electron–hole separation in g‐C 3 N 4 /carbon composites for CO 2 photoreduction . The g‐C 3 N 4 could also be hybridized with CO 2 adsorbents such as layered double hydroxides and metal–organic frameworks (MOFs) considering that the adsorbents would provide a CO 2 ‐rich environment (Figure D–G) .…”

“…The hybridization strategy of g‐C 3 N 4 for CO 2 photoreduction shifts toward band structure engineering for the g‐C 3 N 4 by hybridizing with semiconductors such as red phosphorous, WO 3 , KNbO 3 , UiO‐66, SnO x , Ag 3 PO 4 , AgCl, B 4 C, CdS, CdIn 2 S 4, ZnIn 2 S 4 , Na 10 Co 4 (H 2 O) 2 (PW 9 O 34 ) 2, LaPO 4 , Ag 2 CrO 4 , Cu 2 O, BiCO 4 , ZnV 2 O 6 , FeWO 4 , etc . The formation of heterojunction between the g‐C 3 N 4 and semiconductor induces effective electron–hole separation through the type II heterojunction or light absorption maximized via Z‐scheme, which leads to remarkable enhancement in the catalytic activity of the g‐C 3 N 4 for CO 2 photoreduction (Figure H).…”

Evaluation of polymeric g-C3N4 contained nonhierarchical ZnV2O6 composite for energy-efficient LED assisted photocatalytic mineralization of organic pollutant

“…In the pattern obtained for pure ZnV 2 O 6 , there are numerous weak peaks along with characteristic ones that are in accordance with the standard of ZnV 2 O 6 (JCPDS card 01-074-1262). Also, the weak peaks of V 2 O 5 (JCPDS card 01-072-0433) have appeared that indicated the production of a minute amount of V 2 O 5 [23]. The spectra obtained for the 1:1 (ZnV 2 O 6 /g-C 3 N 4 ) composite is convincing because of the presence of representative bands of both ZnV 2 O 6 and g-C 3 N 4 .…”

“…Prapallely, researchers have tried to tether g-C 3 N 4 with ZnV x O y to obtain a composite or heterojunctions. Explicitly, ZnV 2 O 6 /g-C 3 N 4 nanosheets heterojunctions, ZnV 2 O 6 /RGO/g-C 3 N 4 complex, and ZnV 2 O 6 /rGO composite were very recently applied in photocatalytic CO 2 reduction and dye degradation under visible-light [21][22][23]. Each of these reports highlights on the synergistic action of ZnV 2 O 6 and g-C 3 N 4 in enhancing the photo-mineralization efficiencies.…”

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

“…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 . 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).…”