Magnetic Mn-Incorporated Cs3Cu2Br5 Nanocrystals for Spin-Polarized Enhanced Photocatalytic Biomass Conversion Coupled with H2O2 Evolution

Abstract

Copper-based halide perovskite, as an ideal alternative to lead-based halide perovskite, has attracted much attention in many applications owing to its earth-abundant element, non-toxicity, and excellent optical properties. In this report, magnetic Mn-incorporated lead-free copper halide perovskite (Cs3Cu2Br5) nanocrystal (NC) is for the first time designed and prepared using a one-pot hot-injection route, resulting in a new emission band at ≈540 nm accompanied with self-trapped exciton (STE) emission centered at ≈445 nm from Cs3Cu2Br5 NC. In situ X-ray photoelectron spectroscopy and in situ kelvin probe force microscopy (KPFM) confirm that the Mn2+ incorporation causes efficient electron–hole separation and extended charge lifetime in Mn-doped Cs3Cu2Br5 NC, which exhibits significantly raised selectively photocatalytic biomass conversion coupled with obviously enhanced H2O2 evolution. With an external magnetic field, the spin-polarized electrons in Mn-doped Cs3Cu2Br5 NC arouses reduced charge recombination and more available electrons/holes for surface redox reaction, further raising the photocatalytic performance. This is confirmed by in situ steady-state/transient-state photoluminescence (PL) spectroscopy, in situ transient photocurrent measurement, and in situ electrochemical impedance spectroscopy with external magnetic field. In situ electron paramagnetic resonance (EPR) spectra reveal the radical-involved reaction pathway for biomass conversion. This research exhibits the great potential of spin-polarization-enhanced photocatalysis by an external magnetic field without additional energy consumption.