Chirality-Induced Spin Selectivity of Photo-Generated Electrons in Hybrid Organic-Inorganic Perovskites for Photocatalytic Hydrogen Evolution.

Photocatalytic hydrogen evolution (PHE) is attractive for sustainable energy production, yet its efficiency lags photovoltaic conversion mainly due to the step of H‒H bonding for hydrogen generation on photocatalysts. Herein, the spin-enhanced PHE using photocatalysts of chiral perovskites (MBPI) are reported, where the spin orientations of photocarriers are aligned antiparallelly for H‒H bonding via the chiral-induced spin selectivity (CISS) effect. It is observed that the rac-MBPI shows a 3.5-fold enhancement in PHE activity compared with R/S-MBPI under visible light illumination, which is related to the chiral distortions of octahedral units in perovskite structures. Structural distortions lead to the spin polarization of photogenerated carriers in chiral perovskites due to the CISS effect, as revealed by magneto-photocurrent measurements. Compared with the parallel spins in R/S-MBPI, the antiparallel spins in rac-MBPI are more favorable for the coupling of H* radicals, as proven by the electron paramagnetic resonance experiments. The spin-enhanced mechanism for PHE is universal for reduced dimensional (quasi-2D) chiral perovskites, and the H yield rate is optimized up to 0.61 mmol g h with an excellent stability over 100 hours.