Photocatalytic water splitting for H₂ evolution is appealing for transforming solar energy into clean chemical fuel. This technique generally requires noble metals as H₂ evolution cocatalysts to facilitate efficient cleavage of water. Herein, we report a noble-metal-free TiO₂ nanobelts composite photocatalyst, in which TiO₂ nanobelts are supported by nitrogen-doped graphene coordinated with a single Co atom (Co-NG). The results show that Co-NG is an efficient cocatalytst for the photocatalytic H₂ production over TiO₂. The optimal amount of Co-NG loading is found to be 3.5 wt %, showing a H₂ evolution rate of 677.44 μmol h^–1 g^–1 under illumination of AM 1.5 G simulated sunlight, which is close to that of platinized TiO₂ nanobelts and 2.6 and 31.2 times greater than that of 3.5 wt % NG/TiO₂ nanobelts composite and pure TiO₂ nanobelts, respectively. The significantly improved photocatalytic activity is ascribed to the remarkable synergistic effect between single-atom Co and N-doped graphene, which serve as effective H⁺ reduction sites and efficient electron acceptors, respectively. Besides, the Co-NG cocatalyst also effectively retards the recombination of photoinduced charge carriers and leads to a prolonged lifetime of charge pairs. This study reveals that Co-NG is an up-and-coming candidate as cocatalyst for development of cost-effective photocatalysts for efficient solar-driven H₂ evolution.

中文翻译：

---

用于H ₂释放的高效无贵金属Co-NG / TiO ₂光催化剂：单原子Co和N掺杂石墨烯之间的协同效应，以增强光催化活性

用于分解H _2的光催化水分解技术很有吸引力，可以将太阳能转化为清洁的化学燃料。该技术通常需要贵金属作为H ₂析出助催化剂，以促进水的有效裂解。本文中，我们报道了一种不含贵金属的TiO ₂纳米带复合光催化剂，其中TiO ₂纳米带由掺有单个Co原子（Co-NG）的氮掺杂石墨烯支撑。结果表明，Co-NG是在TiO ₂上光催化生产H ₂的有效助催化剂。发现最佳的Co-NG负载量为3.5 wt％，表明H ₂的析出速率为677.44μmolh ^–1 g在AM 1.5 G模拟阳光的照射下^–1接近于镀铂的TiO ₂纳米带，分别是3.5 wt％NG / TiO ₂纳米复合带和纯TiO ₂纳米带的2.6和31.2倍。显着改善的光催化活性归因于单原子Co和N掺杂石墨烯之间的显着协同作用，这可作为有效的H ⁺还原位点和有效电子受体。此外，Co-NG助催化剂还有效地阻止了光诱导电荷载体的重组，并延长了电荷对的寿命。这项研究表明，Co-NG有望成为开发高效太阳能驱动H ₂的经济有效光催化剂的助催化剂。