Abstract:
Constructing an artificial photosynthetic assembly for efficient photocatalytic water-splitting is a key step in the pursuit for a solar-driven renewable energy economy; however, the paucity of an ideal combination of photosensitizer and catalyst has impeded the technological progress in this field. Here, we have emulated the structural blueprint of the natural photosystem-II to fabricate a covalently linked gold nanoprism-cobalt molecular catalyst construct. This unique congregation of plasmonic photosensitizer with molecular electrocatalyst stimulated efficient photo-electrocatalytic water oxidation reaction, evident from a significant photocurrent generation (~50 �A/cm2) in neutral aqueous condition with minimal onset overpotential requirement (~250 mV). This gold plasmon-cobalt catalyst dyad imitates the light harvesting properties of natural photosystem-II by producing 0.66 �moles of O2 and 1.32 �moles of H2 simultaneously per hour following the complete water-splitting under light with ~0.075-0.01% incident photon to photocurrent conversion efficiency (IPCE). The key presence of the plasmonic gold nanomaterial in this assembly instigates a broadband absorbance spanning from the visible to NIR region (400-1200 nm). Thus, this gold plasmon-cobalt catalyst dyad is one of the rarest examples of a photocatalyst that can absorb the majority of the natural solar light. This data can be translated into 0.8% photon to chemical fuel conversion efficiency for this photocatalytic dyad in neutral aqueous conditions. Both the gold nanoprism and molecular cobalt catalyst retain their intrinsic structural properties in the course of the photo-electrocatalytic water splitting to demonstrate the prospective practical applications of this durable photocatalytic dyad in the alternative energy field.