Surfactant-free synthesis of Cu2O hollow spheres and their wavelength-dependent visible photocatalytic activities using LED lamps as cold light sources

A facile synthesis route of cuprous oxide (Cu2O) hollow spheres under different temperatures without the aid of a surfactant was introduced. Morphology and structure varied as functions of reaction temperature and duration. A bubble template-mediated formation mechanism was proposed, which explained the reason of morphology changing with reaction temperature. The obtained Cu2O hollow spheres were active photocatalyst for the degradation of methyl orange under visible light. A self-designed equipment of light emitting diode (LED) cold light sources with the wavelength of 450, 550, and 700 nm, respectively, was used for the first time in the photocatalysis experiment with no extra heat introduced. The most suitable wavelength for Cu2O to photocatalytic degradation is 550 nm, because the light energy (2.25 eV) is closest to the band gap of Cu2O (2.17 eV). These surfactant-free synthesized Cu2O hollow spheres would be highly attractive for practical applications in water pollutant removal and environmental remediation.