Photocatalytic reductive coupling of carbon-carbon bond to assemble complex molecular frameworks holds the great promising for solar energy storage and value-added chemicals production. This process generally demands noble-photosensitizer or powered by ultraviolet light, along with harsh conditions, which inevitably induces undesired by-product with poor selectivity. Here, we demonstrated selectively reductive aromatic ketones into pinacol on low-cost photocatalysts Ni-doped quantum dots, in which the yield can reach up to 88% with ketones conversion more than 95% under visible-light irradiation for 5 h. A novel mechanism dedicated to the interaction between in situ generated oxidized sacrificial agents TEA^•+ and reactants for key ketyl radical formation via proton-coupled electron transfer (PCET) is elaborately probed by EPR measurement, iotope labeling experiments and DFT calculation. This work emerges a new family of catalysts for C-C coupling by solar energy. More importantly, it provides more credible demonstration for TEA activated photocatalytic conversion in organic synthesis.

碳-碳键的光催化还原偶联组装复杂的分子框架在太阳能存储和增值化学品生产方面具有广阔的前景。该过程通常需要贵重的光敏剂或由紫外线驱动，以及恶劣的条件，这不可避免地会产生选择性差的不想要的副产物。在这里，我们展示了在低成本光催化剂 Ni 掺杂的量子点上选择性还原芳香酮为频哪醇，在可见光照射 5 小时下，产率可达 88%，酮转化率超过 95%。一种致力于原位生成的氧化牺牲剂 TEA ^•+之间相互作用的新机制通过 EPR 测量、同位素标记实验和 DFT 计算精心探测了通过质子耦合电子转移 (PCET) 形成关键羰基自由基的反应物。这项工作出现了一个新的太阳能 CC 耦合催化剂系列。更重要的是，它为有机合成中的 TEA 活化光催化转化提供了更可信的证明。