Carbon　dots　with　various　functional　groups　can　be　employed　as　the　potential　sensitizer.　In　this　study,　carbon　dots　are　obtained　by　electrochemical　ablation　of　graphite　rods　in　alkaline　electrolyte.　The　better　preparation　condition　is　the　applied　potential　of　40　V　and　the　ablation　time　of　5　h.　TiO2　nanotube　arrays　and　TiO2　nanoparticles　photoelectrodes　are　sensitized　by　the　as-prepared　carbon　dots　through　using　impregnation　method.　Carbon　dots/TiO2　nanotube　arrays　electrodes　exhibit　greater　photoelectrochemical　hydrogen　production　activities　than　carbon　dots/TiO2　nanoparticles　electrodes.　It　is　because　more　carbon　dots　can　be　well　combined　with　TiO2　nanotube　arrays.　Based　on　the　IPCE　values　in　visible　light　region,　the　role　of　carbon　dots　on　TiO2　nanotube　arrays　electrode　depends　on　the　up-converted　PL　behaviors　from　their　surface　states　and　the　alkaline　electrolyte.　The　results　provide　insight　into　carbon　dots　that　serve　as　sensitizer　of　TiO2　photoelectrode　in　water　splitting　system　of　alkaline　solution.　(C)　2017　Hydrogen　Energy　Publications　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.