Network structured CuWO₄ /BiVO₄/Co-Pi nanocomposite for solar water splitting

A network structured CuWO₄ /BiVO₄ nanocomposite with a high specific surface area was prepared from CuWO₄ nanoflake (NF) arrays via a method that combined drop-casting and thermal annealing. The obtained CuWO₄ /BiVO₄ exhibited high catalytic activity toward photoelectrochemical (PEC) water oxidation. When cobalt phosphate (Co-Pi) was coupled with CuWO₄ /BiVO₄, the activity of the resulting CuWO₄ /BiVO₄ /Co-Pi composite for the oxygen evolution reaction (OER) was further improved. The photocurrent density (J_ph) for OER on CuWO₄ /BiVO₄ /Co-Pi is among the highest reported on a CuWO₄-based photoanode in a neutral solution. The high activity for the PEC OER was attributed to the high specific surface area of the composite, the formation of a CuWO₄ /BiVO₄ heterojunction that accelerated electron–hole separation, and the coupling of the Co-Pi co-catalyst with CuWO₄ /BiVO₄, which improved the charge transfer rate across composite/solution interface.