One-step hydrothermal synthesis of Bi2WxMo1-xO6 solid solution with adjustable energy band coupling with g-C3N4: 2D/2D Z-scheme heterojunction for enhanced photocatalytic HCHO degradation under indoor conditions

In this work, 2D/2D Bi2WxMo1-xO6/g-C3N4 was synthesized via surfactant-assisted one-step hydrothermal method for the degradation of formaldehyde in simulated room environment. We utilized CTAC as surfactant to control the morphologies of Bi2WxMo1-xO6 coupling with g-C3N4 nanosheets. In the hydrothermal method, Mo replaced W to form solid solution which could reduce energy band gap of Bi2WO6. In contrast to Bi2W0.6Mo0.4O6 (43.1%) and g-C3N4 (23.2%), Bi2W0.6Mo0.4O6/g-C3N4 exhibited superior activity (92.4%) of photocatalytic degradation for formaldehyde at the initial concentration of 1 ppm under the relative humidity (RH) of 20%. Meanwhile, we simulated diverse typical indoor conditions to evaluate the applicability of catalysts. More importantly, Bi2W0.6Mo0.4O6/g-C3N4 performed satisfactory stability with 5.5% decrease in degradation effi-ciency after five cycles. The mechanism of enhanced HCHO conversion was ascribed to the formation of 2D/2D Z-scheme heterojunction between Bi2W0.6Mo0.4O6 and g-C3N4 which increased the accessible interface and promoted the separation of photo-generated carriers for oxidation of formaldehyde.

Automated summary

In this study, 2D/2D Bi2WxMo1-xO6/g-C3N4 nanocomposites were synthesized using surfactant-assisted one-step hydrothermal method for the degradation of formaldehyde in simulated room environment. CTAC surfactant was used to control the morphologies of Bi2WxMo1-xO6 coupling with g-C3N4 nanosheets. The solid solution of W and Mo in Bi2WxMo1-xO6 reduced the energy band gap of Bi2WO6. Compared to Bi2W0.6Mo0.4O6 (43.1%) and g-C3N4 (23.2%), Bi2W0.6Mo0.4O6/g-C3N4 exhibited superior photocatalytic activity (92.4%) for formaldehyde degradation at an initial concentration of 1 ppm and relative humidity of 20%. The catalyst also demonstrated satisfactory stability with only a 5.5% decrease in degradation efficiency after five cycles. The enhanced HCHO conversion was attributed to the formation of a 2D/2D Z-scheme heterojunction between Bi2W0.6Mo0.4O6 and g-C3N4, which increased the accessible interface and promoted the separation of photo-generated carriers for oxidation of formaldehyde.