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 Cu 2−x Se/Cu 2 O heterojunction photocatalyst. Nonstoichiometric Cu 2−x Se crystals are grown from a pliable Cu mesh through a self-sacrifice template strategy. Sintering Cu 2−x Se in O 2 /N 2 atmosphere enables the formation of Cu 2−x Se/Cu 2 O heterojunction. The implantation of Cu 2 O lowers the work function of Cu 2−x Se 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 Cu 2−x Se/Cu 2 O delocalize to attract formaldehyde molecules and convert them into semi-stable carbonates. Simultaneously, these electrons react with adsorbed oxygen to produce active •O 2 - . With a continuous-flow operation mode, 100% removal percentage and 99.5% CO 2 conversion rate are achieved when eliminating formaldehyde. By virtue of its integrity and pliability, the Cu mesh bearing Cu 2−x Se/Cu 2 O can be applied in air purifier directly. • An innovative Cu 2−x Se/Cu 2 O/Cu mesh photocatalyst was prepared. • Cu 2 O is implanted in Cu 2−x Se crystals by sharing same Cu atoms with Cu 2−x Se. • Cu 2−x Se/Cu 2 O junctions are electron-rich area under irradiation. • Abundant electrons delocalize to anchor and decompose formaldehyde. • Solid and pliable Cu 2−x Se/Cu 2 O/Cu mesh is viable for designing an air purifier.