Synergizing Donor–Acceptor Ni‐MOF with Lignin Proton Relay for Efficient and Selective CO ₂ ‐to‐CO Photoreduction

Abstract

Abstract Amidst the urgent global push for carbon neutrality, CO 2 ‐to‐CO photoreduction has emerged as a critical technology for closing the carbon cycle and converting renewable energy. In this work, a hybrid catalyst, denoted as C‐HL‐20%/Ni(TTA)bpe (TTA = 4,4′,4″;‐tricarboxy‐triphenylamine, bpe = 4,4′‐ethylenedipyridine), is constructed through the rational design of a composite system incorporating carboxylated lignin (C‐HL) and a single‐crystalline Ni‐based metal–organic framework (Ni‐MOF). The catalyst demonstrates impressive photocatalytic performance, achieving a CO production rate of 6516.4 µmol g −1 h −1 with 98.3% selectivity, which has reached the top level of the reported MOF‐based photocatalysts. Under outdoor conditions, it also demonstrates a stable CO 2 ‐to‐CO conversion rate of 4282.5 µmol g −1 h −1 . Experimental characterizations and theoretical calculations reveal that this high activity originates from donor–acceptor (D–A) artificial structure of the single‐crystalline Ni‐MOF and proton‐coupled electron transfer (PCET) process. Modification with C‐HL introduces enriched ─COOH groups, which form hydrogen bonds with the Ni(TTA)bpe framework. This not only consolidates the structure but also shortens the electron migration pathway, thereby achieving efficient and selective CO 2 ‐to‐CO photo‐conversion. This study establishes a rational catalyst design strategy for sustainable CO 2 photoreduction, demonstrating a feasible pathway toward manageable carbon resource utilization.