Photosynthetic Biomimetic System: Nickel Phthalocyanine and Biomass‐Derived Carbon Quantum Dots for Enhanced Water Oxidation

Abstract Efficient water oxidation is a crucial challenge for artificial photosynthesis and solar energy conversion. Here, we introduce a biomimetic photosynthetic system that combines Nickel(II) phthalocyanine‐tetrasulfonic acid (NiPc) with carbon quantum dots (CQDs) derived from sugarcane biomass to enhance photoelectrochemical water oxidation. The CQDs effectively absorb UV and visible light, aiding electron transfer to NiPc, which significantly boosts photocurrent generation and reduces the overpotential. Electrochemical tests, including cyclic voltammetry and chronoamperometry under UV and blue light, show that the NiPc/CQD hybrid system delivers a notable increase in photocurrent density and stability compared to bare NiPc electrodes. By a membrane‐free Clark‐type electrode, molecular oxygen generated during photoelectrochemical water oxidation was detected. This sustainable system underscores the potential of biomass‐derived CQDs as efficient, low‐cost nanomaterials for solar‐driven water oxidation, advancing renewable energy technologies.