Polymeric carbon nitride (CN) emerged as an alternative, metal-free photoanode material for water-splitting photoelectrochemical cells (PECs). However, the performance of CN photoanodes is limited due to the slow charge separation and water oxidation kinetics due to poor interaction with water oxidation catalysts (WOCs). Moreover, operation under benign, neutral pH conditions is rarely reported. Here, we design a porous CN photoanode connected to a highly active molecular Ru-based WOC, which also acts as an additional photo-absorber. We show that the strong interaction between the π-system of the heptazine units within the CN with the CH groups of the WOC's equatorial ligand enables a strong connection between them and an efficient electronic communication path. The optimized photoanode exhibits a photocurrent density of 180 ± 10 μA cm⁻² at 1.23 V vs. the reversible hydrogen electrode (RHE) with 89% faradaic efficiency for oxygen evolution with turnover numbers (TONs) in the range of 3300 and a turnover frequency (TOF) of 0.4 s⁻¹, low onset potential, extended incident photon to current conversion, and good stability up to 5 h. This study may lead to the integration of molecular catalysts and polymeric organic absorbers using supramolecular interactions.

中文翻译：

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分子催化剂与聚合氮化碳光阳极的超分子相互作用增强了中性 pH 下的光电化学活性和稳定性


聚合氮化碳（CN）成为水分解光电化学电池（PEC）的替代无金属光电阳极材料。然而，由于与水氧化催化剂（WOC）的相互作用较差，导致电荷分离缓慢和水氧化动力学缓慢，CN光阳极的性能受到限制。此外，在良性、中性pH条件下进行操作的报道也很少。在这里，我们设计了一个多孔 CN 光阳极，连接到高活性分子 Ru 基 WOC，它也充当额外的光吸收剂。我们表明，CN 内七嗪单元的 π 系统与 WOC 赤道配体的 CH 基团之间的强相互作用使它们之间形成牢固的连接并形成有效的电子通信路径。优化的光阳极在 1.23 V 下表现出 180 ± 10 μA cm ^-2的光电流密度，与可逆氢电极 (RHE)相比，析氧法拉第效率为 89%，周转数 (TON) 和周转频率在 3300 范围内(TOF) 为 0.4 s ^-1 ，起始电势低，入射光子到电流的转换时间延长，并且稳定性良好，长达 5 小时。这项研究可能会导致利用超分子相互作用将分子催化剂和聚合物有机吸收剂结合起来。