So-called Z-scheme systems, which typically comprise an H₂ evolution photocatalyst (HEP), an O₂ evolution photocatalyst (OEP), and an electron mediator, represent a promising approach to solar hydrogen production via photocatalytic overall water splitting (OWS). The electron mediator transferring photogenerated charges between the HEP and OEP governs the performance of such systems. However, existing electron mediators suffer from low stability, corrosiveness to the photocatalysts, and parasitic light absorption. In the present work, carbon nanotubes (CNTs) were shown to function as an effective solid-state electron mediator in a Z-scheme OWS system. Based on the high stability and good charge transfer characteristics of CNTs, this system exhibited superior OWS performance compared with other systems using more common electron mediators. The as-constructed system evolved stoichiometric amounts of H₂ and O₂ at near-ambient pressure with a solar-to-hydrogen energy conversion efficiency of 0.15%. The OWS reaction was also promoted in the case that this CNT-based Z-scheme system was immobilized on a substrate. Hence, CNTs are a viable electron mediator material for large-scale Z-scheme OWS systems.

中文翻译：

---

碳纳米管作为可见光驱动 Z 型整体水分解的固态电子介体


所谓的 Z 型系统通常包含 H ₂ 演化光催化剂 (HEP)、O ₂ 演化光催化剂 (OEP) 和电子介体，代表了一种有前途的方法通过光催化全水分解（OWS）太阳能制氢。在 HEP 和 OEP 之间传输光生电荷的电子介体控制着此类系统的性能。然而，现有的电子介体存在稳定性低、对光催化剂有腐蚀性以及寄生光吸收等问题。在目前的工作中，碳纳米管（CNT）被证明可以在 Z 型 OWS 系统中充当有效的固态电子介体。基于碳纳米管的高稳定性和良好的电荷转移特性，与其他使用更常见电子介体的系统相比，该系统表现出优越的OWS性能。所构建的系统在接近环境压力下产生化学计量的H ₂ 和O ₂ ，太阳能到氢能的转换效率为0.15%。当这种基于CNT的Z型系统固定在基底上时，OWS反应也得到促进。因此，碳纳米管是用于大规模 Z 型 OWS 系统的可行电子介体材料。