Self-Assembled α-Fe2O3@Co3O4/Graphene Quantum Dot Core-Hybrid Shell Wormlike Nanoarrays with Synergistic Effects for Photoelectrochemical Water Oxidation

Hematite (& alpha;-Fe2O3) core-cocatalystshell nanoarchitectures with ultrathin hybrid shells are promisingto maximize photoelectrochemical (PEC) water oxidation performanceof Fe2O3-based photoelectrodes, but their fabricationpresents formidable challenges. For the first time, a wormlike nanostructured & alpha;-Fe2O3@Co3O4/graphenequantum dot (GQD) core-hybrid shell nanoarray is synthesizedvia self-assembly, showing an onset potential of 0.63 V (vs the reversiblehydrogen electrode (RHE)) and a photocurrent density of 3.63 mA cm(-2) at 1.23 V (vs RHE). This performance is superiorto those of reported Fe2O3-based heterojunctionphotoanodes and among the best reported for Fe2O3-based photoanodes. The outstanding performance is due to the Co3O4/GQD shell significantly promoting charge separationand transfer and hole injection as well as great synergistic effectsbetween GQDs and Co3O4. This work not only fabricatesa low-cost photoanode with record-high water oxidation performanceand offers scientific insights into the enhancement mechanism butalso provides a facile, economical, and universal strategy to self-assembleconformal, ultrathin hybrid shells on three-dimensional (3-D) complexnanostructures, which have broad applications in the fields of energy,environment, and sensing. & alpha;-Fe2O3@Co3O4/GQD core-hybridshell wormlike nanoarrays were synthesizedvia coordination and electrostatic force-driven self-assembly, showingsuperior PEC water oxidation performance.