Metal-Free 2D/2D Black Phosphorus and Covalent Triazine Framework Heterostructure for CO2 Photoreduction

Photoreduction of CO2 to CH4, which is an 8-electron photoelectrochemical process, represents one of the most appealing approaches that tackles the global warming challenge and fuel crisis. To achieve this, highly efficient and selective catalysts are desired. In this work, we successfully developed a metal-free 2D/2D heterostructured catalyst for photoreduction of CO2 to CH4 with black phosphorus (BP) and covalent triazine framework (CTF). The synthesized CTF-BP heterostructure catalyst was well characterized using the high-resolution TEM (HRTEM), AFM, XPS and Raman. Compared with the pristine BP or CTF, the photoreduction of CO2 to CO rate over the CTF-BP catalyst (4.60 μmol g–1 h–1) is 3 and 2 times higher than those over BP and CTF catalysts, respectively. The photoreduction of CO2 to CH4 rate over the CTF-BP catalyst (7.81 μmol g–1 h–1) is 23 times and 16 times higher than those over BP and CTF catalysts, respectively. This indicates that the CTF-BP heterostructure dramatically enhances the photocatalytic selectivity for CO2 to CH4 over CO. The present work not only develops a metal-free highly efficient and selective catalyst for photoreduction of CO2 but also provides a new heterostructure engineering route for designing and synthesizing highly active and metal-free catalysts applied in sustainable solar-to-chemical energy conversion and environmental remediation.