Synthesis and optical properties of electrodeposited crystalline Cu2O in the Vis–NIR range for solar selective absorbers

• Microstructural characterization of electrodeposited Cu2O/Cu tandem.
• Time-dependent spectral absorptivity of Cu2O/Cu for solar absorbers.
• Annealing of Cu2O into CuO.

This paper reports on the thermal oxidation of electrodeposited copper microstructures from a 0.2 M H2SO4 + 0.4 M CuSO4 aqueous solution on a copper substrate for selective solar thermal absorbers applications. A study of the morphological properties and crystalline structure of the deposited/annealed layer through SEM-EDS and powder XRD revealed the formation of self-assembled cubic Cu2O microstructures. The copper oxide layer was optically examined by virtue of a spectrometer in the spectral Vis–NIR range. The surface roughness induced by the existence of the globular microstructure has been seen to enhance the absorptance of the material. Around two to three-fold enhancement of optical surface absorption is achieved in the wavelength range of 400–1000 nm versus an air-grown copper oxide.