By　means　of　density　functional　theory　(DFT)　computations,　we　investigated　the　functionalization　effects　of　relatively　non-toxic　organic　molecules　(C6H5COOH　and　C6H5OCH3)　on　the　photocatalytic　performance　of　monolayer　MoS2.　It　is　found　that　C6H5COOH　and　C6H5OCH3　both　are　physically　adsorbed　on　the　surface　of　MoS2.　The　functionalization　of　C6H5COOH　and　C6H5OCH3　on　monolayer　MoS2　not　only　facilitate　the　separation　of　photoinduced　carriers　and　improve　the　optical　adsorption　ability,　but　also　make　the　band　positions　enough　to　drive　water　split　into　H-2　and　O-2.　Thus,　we　propose　that　the　C6H5COOH/MoS2　and　C6H5OCH3/MoS2　can　be　potential　photocatalysts　for　overall　water　splitting　under　visible　light.　(C)　2017　Elsevier　B.V.　All　rights　reserved.