Multiple chemical valences induced interface regulation in perovskite nickelate/carbon nitride for boosting...

Recent developments in transition metal-based photocatalysts have heightened the need for superior solar utilization. Evidence suggests that properly adjusting the chemical valence of the transition metal elements could simultaneously achieve broad-spectrum absorption and efficient charge separation for the photocatalysts. However, the understanding and application of this strategy remain a significant challenge. Herein, a series of La_0.9Ni_0.8Co_0.2O_3-α/g-C₃N₄ (LNCO/CN) composites were synthesized employing a mild reduction procedure in the H_2/Ar atmosphere. Experimental studies reveal that the composites regulated by interfacial coordination unsaturation Ni²⁺ and metal Ni⁰ possess accelerated Z-scheme charge transfer through the interfacial bond between Ni²⁺ and N. Besides, the localized-surface-plasmon-resonance-induced "hot electrons" injection process of in situ grown Ni⁰ nanoparticle is confirmed, which can efficiently quench the photoinduced holes and create hole vacancies around the interface. Due to the synergistic effect between Ni²⁺ and Ni⁰, the lifetime of the photo-excited electrons is prolonged with inhibited recombination behavior. After modulation, optimal LNCO/CN Z-scheme hybrid exhibits 9-fold promotion of photocatalytic hydrogen evolution rate compared to pristine LNCO/CN. This study gives valuable insight into the purposeful utilization of the chemical valence modulating strategy, which alters the chemical valence of transition metal elements to enhance the performance of perovskite-based photocatalysts dramatically.