Congregated-electrons-strengthened anchoring and mineralization of gaseous formaldehyde on a novel self-supporting Cu2-xSe/Cu2O heterojunction photocatalyst under visible lights: A viable mesh for designing air purifier

Reinforced adsorption enabled efficient degradation of formaldehyde was investigated with a unique flower-like Cu2−xSe/Cu2O heterojunction photocatalyst. Nonstoichiometric Cu2−xSe crystals are grown from a pliable Cu mesh through a self-sacrifice template strategy. Sintering Cu2−xSe in O2/N2 atmosphere enables the formation of Cu2−xSe/Cu2O heterojunction. The implantation of Cu2O lowers the work function of Cu2−xSe and boosts the gathering of electrons, qualifying the heterojunction as electron-rich area with those shared Cu atoms being active sites. Under illumination, abundant electrons on Cu2−xSe/Cu2O delocalize to attract formaldehyde molecules and convert them into semi-stable carbonates. Simultaneously, these electrons react with adsorbed oxygen to produce active •O2-. With a continuous-flow operation mode, 100% removal percentage and 99.5% CO2 conversion rate are achieved when eliminating formaldehyde. By virtue of its integrity and pliability, the Cu mesh bearing Cu2−xSe/Cu2O can be applied in air purifier directly. [Display omitted] •An innovative Cu2−xSe/Cu2O/Cu mesh photocatalyst was prepared.•Cu2O is implanted in Cu2−xSe crystals by sharing same Cu atoms with Cu2−xSe.•Cu2−xSe/Cu2O junctions are electron-rich area under irradiation.•Abundant electrons delocalize to anchor and decompose formaldehyde.•Solid and pliable Cu2−xSe/Cu2O/Cu mesh is viable for designing an air purifier.