Efficient in situ deposition of metallic cocatalyst, like zero‐valent platinum (Pt), on organic photovoltaic catalysts (OPCs) is the prerequisite for their high catalytic activities. Here we develop the OPC (Y6CO), by introducing carbonyl in the core, which is available to σ‐π coordinate with transition metals, due to the high‐energy empty π* orbital of carbonyl. Y6CO exhibits a stronger capability to anchor Pt species and reduce them to metallic state, resulting in more Pt0 deposition, relative to the control OPC without the central σ‐π anchor. Single‐component and heterojunction nanoparticles (NPs) employing Y6CO show enhanced average hydrogen evolution rates of 230.98 and 323.22 mmol h−1 g[OPC]−1, respectively, under AM 1.5G, 100 mW cm−2 for 10 h, and heterojunction NPs yield the external quantum efficiencies of ca. 10 % in 500–800 nm. This work demonstrates that σ‐π anchoring is one efficient strategy for integrating metallic cocatalyst and OPC for high‐performance photocatalysis.

Efficient in situ deposition of metallic cocatalyst, like zero-valent platinum (Pt), on organic photovoltaic catalysts (OPCs) is the prerequisite for their high catalytic activities. Here we develop the OPC (Y6CO), by introducing carbonyl in the core, which is available to σ-π coordinate with transition metals, due to the highenergy empty π* orbital of carbonyl. Y6CO exhibits a stronger capability to anchor Pt species and reduce them to metallic state, resulting in more Pt 0 deposition, relative to the control OPC without the central σ-π anchor. Single-component and heterojunction nanoparticles (NPs) employing Y6CO show enhanced average hydrogen evolution rates of 230.98 and 323.22 mmol h À 1 g [OPC] À 1 , respectively, under AM 1.5G, 100 mW cm À 2 for 10 h, and heterojunction NPs yield the external quantum efficiencies of ca. 10 % in 500-800 nm. This work demonstrates that σ-π anchoring is one efficient strategy for integrating metallic cocatalyst and OPC for high-performance photocatalysis.