An Inorganic-Organic Hybrid Polymer Cocatalyst for Photoelectrochemical Water Oxidation with Dual Functions of Accelerating Kinetics and Improving Charge Transfer

Abstract

Oxygen evolution cocatalysts (OECs) play important roles in improving the efficiency of photocatalysts in solar water splitting. Inorganic-organic hybrid polymers (IOHPs), which have good electrolyte accessibility and evenly distributed active sites, are expected to be promising OECs. Here, a novel IOHP [Co(Bpn)2(SCN)2]n (1, Bpn = 2,6-bis(4-pyridyl)- naphthalene, SCN = thiocyanate ion) exhibited a two-dimensional (2D) layer structure with (4, 4) topology, was constructed by Bpn ligands connecting Co(II) ions, and was decorated on BiVO4 photoanodes for photoelectrochemical (PEC) water oxidation. The 1/BiVO4 hybrid electrode showed significantly negative onset potential and approximately 3.7 times higher photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) compared with the bare BiVO4. The mechanisms for the improved PEC efficiency were investigated and mainly ascribed to enhanced water oxidation kinetics and increased charge separation and transfer properties. This work provides a promising OEC candidate for PEC water oxidation and sheds light on the attractive application prospect of IOHPs for solar water splitting.