Prolonged lifetime and enhanced separation of photogenerated charges of nanosized α-Fe2O3 by coupling SnO2 for efficient visible-light photocatalysis to convert CO2 and degrade acetaldehyde

To develop efficient visible-light photocatalysis on α-Fe 2 O 3 , it is highly desirable to promote visible-light-excited high-energy-level electron transfer to a proper energy platform thermodynamically. Herein, based on the transient-state surface photovoltage responses and the atmosphere-controlled steady-state surface photovoltage spectra, it is demonstrated that the lifetime and separation of photogenerated charges of nanosized α-Fe 2 O 3 are increased after coupling a proper amount of nanocrystalline SnO 2 . This naturally leads to greatly improved photocatalytic activities for CO 2 reduction and acetaldehyde degradation. It is suggested that the enhanced charge separation results from the electron transfer from α-Fe 2 O 3 to SnO 2 , which acts as a proper energy platform. Based on the photocurrent action spectra, it is confirmed that the coupled SnO 2 exhibits longer visible-light threshold wavelength (~590 nm) compared with the coupled TiO 2 (~550 nm), indicating that the energy platform introduced by SnO 2 would accept more photogenerated electrons from α-Fe 2 O 3 . Moreover, electrochemical reduction experiments proved that the coupled SnO 2 possesses better catalytic ability for reducing CO 2 and O 2 . These are well responsible for the much efficient photocatalysis on SnO 2 -coupled α-Fe 2 O 3 .