C,　H,　and　O　elements　are　the　three　important　elements　that　make　up　matter,　following　the　conservation　of　matter　and　energy,　and　they　form　common　molecules　such　as　water,　hydrogen,　oxygen,　and　carbon　dioxide　through　chemical　bonds.　At　present,　mankind　is　facing　the　double　challenges　of　energy　shortage　and　environmental　damage,　and　it　is　the　common　development　goal　of　all　mankind　to　use　the　continuous　flow　of　solar　energy　to　achieve　energy　saving　and　carbon　reduction　in　the　fields　of　energy　and　environmental　protection,　until　energy　freedom　and　carbon　neutrality.　This　paper　lists　the　latest　research　progress　of　photocatalytic　technology　in　four　frontier　areas,　namely　hydrogen　(H2)　production,　carbon　dioxide　(CO2)　reduction,　organics　degradation　and　hydrogen　peroxide　(H2O2)　production,　and　recognizes　its　important　role　in　energy　and　environmental　fields　from　the　perspective　of　the　recombination　of　C,　H,　and　O　elements.　The　basic　reaction　mechanisms,　catalyst　types　and　structures,　and　performance　enhancement　strategies　of　each　technology　are　summarized,　and　the　future　development　trends　and　prospects　of　these　technologies　are　outlined.　©　2024　Elsevier　B.V.