Boosting the Activity and Stability of Copper Tungsten Nanoflakes toward Solar Water Oxidation by Iridium-Cobalt Phosphates Modification

Chao Li,Peng Diao

doi:10.3390/catal10080913

Abstract

Severe interfacial electron–hole recombination greatly limits the performance of CuWO4 photoanode towards the photoelectrochemical (PEC) oxygen evolution reaction (OER). Surface modification with an OER cocatalyst can reduce electron–hole recombination and thus improve the PEC OER performance of CuWO4. Herein, we coupled CuWO4 nanoflakes (NFs) with Iridium–cobalt phosphates (IrCo-Pi) and greatly improved the photoactivity of CuWO4. The optimized photocurrent density for CuWO4/IrCo-Pi at 1.23 V vs. reversible hydrogen electrode (RHE) rose to 0.54 mA∙cm−2, a ca. 70% increase over that of bare CuWO4 (0.32 mA∙cm−2). Such improved photoactivity was attributed to the enhanced hole collection efficiency, which resulted from the reduced charge-transfer resistance via IrCo-Pi modification. Moreover, the as-deposited IrCo-Pi layer well coated the inner CuWO4 NFs and effectively prevented the photoinduced corrosion of CuWO4 in neutral potassium phosphate (KPi) buffer solution, eventually leading to a superior stability over the bare CuWO4. The facile preparation of IrCo-Pi and its great improvement in the photoactivity make it possible to design an efficient CuWO4/cocatalyst system towards PEC water oxidation.

Highlights

Photoelectrochemical (PEC) water splitting is a green way to convert solar power into storable chemical fuels and addresses the rising demand for renewable energy [1,2]
We reveal that the greatly-enhanced hole-collection efficiency, which originates from the reduced charge-transfer resistance, accounts for the advanced PEC oxygen evolution reaction (OER) activity
The results presented here, as far as we know, stand as the best enhancement ever achieved on cocatalyst-modified CuWO4

Summary

Introduction

Photoelectrochemical (PEC) water splitting is a green way to convert solar power into storable chemical fuels and addresses the rising demand for renewable energy [1,2]. The solar-to-chemical conversion efficiency for PEC OER undoubtedly depends on the employed photoanode material. 2.7 eV) [7,8,9] and narrow pH range for stable work (pH < 4), restrict its large-scale application [15]. To address such limitations, it is feasible to associate another transition-metal oxide with WO3 to generate a WO3 -based ternary oxide, as the introduced metallic component can regulate the bandgap structure and bonding state of WO3 without damaging its main merits [16,17,18,19]

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Results

Conclusion