Oxygen vacancy rich Cu₂O based composite material with nitrogen doped carbon as matrix for photocatalytic H₂ production and organic pollutant removal

Abstract

A nitrogen doped carbon matrix supported Cu₂O composite material (Cu/Cu2O@NC) was fabricated successfully with a coordination polymer as precursor through calcination. In this composite material, Cu₂O particles with a size of about 6-10 nm were dispersed evenly in the nitrogen doped carbon matrix. After calcination, some coordinated nitrogen atoms were doped in the lattice of Cu₂O and replace oxygen atoms, thus generating a large number of oxygen vacancies. In Cu/Cu2O@NC, the existence of oxygen vacancies has been confirmed by electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS). Under visible light irradiation, Cu/Cu2O@NC exhibits excellent H₂ production with the rate of 379.6 μmol h^-1 g^-1. Its photocatalytic activity affects organic dyes, such as Rhodamine B (RhB) and methyl orange (MO). In addition to photocatalysis, Cu/Cu2O@NC also exhibits striking catalytic activity in reductive conversion of 4-nitrophenol to 4-aminophenol with in presence of sodium borohydride (NaBH₄). The conversion efficiency reaches almost 100% in 250 s with the quantity of Cu/Cu2O@NC as low as 5 mg. The outstanding H₂ production and organic pollutants removal are attributed to the oxygen vacancy. We expect that Cu/Cu2O@NC will find its way as a new resource for hydrogen energy as well as a promising material in water purification.