NOVELTY - A photoelectrochemical material comprises porous network of bismuth vanadate particles. The particles have a mean particle size of less than 150 nm. The porous network has a surface area of 10 m2/g or more as measured by the BET method.    USE - Photoelectrochemical material is used in photoelectrode e.g. photoanode of photoelectrochemical cell for electrochemical reactions (all claimed) e.g. water-splitting reactions.    ADVANTAGE - The material can absorb broader spectrum of solar radiation and has higher solar-to-hydrogen (STH) efficiency, improved electron-hole separation yield and water oxidation efficiency. The material has bismuth vanadate particles having high surface area.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) photoelectrochemical cell, which comprises a working photoelectrode which is the photoelectrochemical material, a counter electrode in electrical communication with the working photoelectrode and an electrolyte solution in which the working photoelectrode and the counter electrode are immersed;    (2) electrochemical reactions, which involves exposing the photoelectrode to radiation having energy more than the band gap of bismuth vanadate so that bismuth vanadate particles absorb the radiation to produce electron-hole pairs and the holes are transported to the electrolyte-photoelectrode interface to undergo oxidation reactions with the electrolyte, and the electrons are transported to the counter electrode to undergo reduction reactions with the electrolyte; and    (3) manufacture of photoelectrochemical material, which involves applying an organic solution comprising vanadium-containing precursor molecules to the surface of a porous network of plate-like bismuth oxide containing crystal of formula: BiOX (I), where X is halogen atom or a mixture of halogen atoms, and heating the applied organic solution and the porous network of plate-like crystals to convert the porous network of plate-like crystals into a porous network of bismuth vanadate particles.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view explaining the synthesis of photoelectrochemical material.