Engineered "Molecule-Junction" to Transport Photo-Generated Electrons for CO₂ Reduction to Ethane

Targeted transport of electrons is essential to enable the photoreduction process efficiently, which remains a significant challenge in current research. Constructing "molecule-junction" between photocatalyst and metal active sites is expected to achieve the precise directional electron transfer. 2-Mercaptonicotinic acid (H₂L), with both sulfhydryl groups (─SH) and a conjugated pyridine ring, was introduced as the intermediary to build "molecule-junction" connecting Ni-doped BiOCl (Ni/BOC) and Au NPs (denoted as Ni/BOC-H₂L-Au). XPS and XAFS results confirm the existence of Bi─S and Au─S bonds, which verify that the "molecule-junction" of Bi─H₂L─Au have been successfully constructed in Ni/BOC. Due to the unique structure of Ni/BOC-H₂L-Au, it showed excellent performance in CO₂ photoreduction. In the absence of sacrificial agents, the ethane (C₂H₆) yield (155.4 µmol g^-1 h^-1) and selectivity (85.8%) exceeded most of the reported photocatalysts. The combined theoretical and experimental analysis demonstrates that the "molecule-junction" establishes a directional electron transfer pathway (Ni/BOC→H₂L→Au NPs), which significantly enhances charge separation efficiency and promotes targeted electron accumulation at Au NPs active sites, thereby boosting C₂H₆ production via CO₂ photoreduction. This work proposes a viable strategy for designing efficient photocatalysts for high-value C₂₊ product synthesis.