Strategically Advancing Semiconducting Phthalocyanines as High-Performance Electrocatalysts for Electrochemical CO ₂ Reduction

Phthalocyanines (Pcs) are promising organic molecular catalysts owing to their well-defined structure and metal–nitrogen sites. However, their application in energy conversion processes, such as electrochemical CO2 reduction (ECR), is severely hindered by intrinsically limited semiconducting conductivity. Conventional chemical intuitions suggest that effective catalytic performance can only be achieved through molecular-level dispersion of Pcs on carbon supports; nevertheless, such strategies are inherently difficult to scale in practical systems. To overcome these challenges, herein, we propose two complementary approaches that fundamentally enhance the performance of Pc-based electrocatalysts. First, crystallization engineering is employed to construct multilayer cobalt phthalocyanine (CoPc) assemblies that form crystallized architectures on conductive substrates. This design markedly improves charge transport, thereby enhancing ECR activity, while simultaneously offering a scalable and practical route for fabricating Pc crystal electrodes. Second, the incorporation of pyridinic nitrogen into the Pc macrocycle yields cobalt tetra-aza-phthalocyanine (CoTAP). This catalyst exhibits record-high current density, mass activity, and operational stability, which can be attributed to an optimized electronic structure and more favorable adsorption of reaction intermediates. Collectively, these strategies overcome the intrinsic semiconducting limitations of conventional Pcs and establish a scalable framework for advancing molecular electrocatalysts toward high-performance electrochemical CO2 reduction technologies.