Copper phosphides are promising materials for energy conversion applications because of their unique electronic structure and controllable composition. Two stoichiometric copper phosphides, CuP
2 and Cu
3P, were prepared by direct wet-chemical synthesis using red phosphorus. They were characterized by powder X-ray
[...] Read more.
Copper phosphides are promising materials for energy conversion applications because of their unique electronic structure and controllable composition. Two stoichiometric copper phosphides, CuP
2 and Cu
3P, were prepared by direct wet-chemical synthesis using red phosphorus. They were characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. The precursor selection, reaction temperature, time and solvent composition were also studied. CuP
2 is the thermodynamically more stable product, but Cu
3P is more commonly obtained. This work demonstrated that higher temperature helps in CuP
2 formation. More importantly, using more trioctylphosphine oxide helps control the morphology leading to crystal growth along the crystallographic a-axis. CuP
2 and Cu
3P were tested for hydrogen evolution, oxygen evolution, and oxygen reduction reactions. CuP
2 works better for HER in acidic conditions and OER in general, and Cu
3P showed better activity than CuP
2 for HER and ORR in an alkaline medium. This study has led to a simple approach to the synthesis of CuP
2 nanowires.
Full article