The　nanocomposites　of　TiO2-graphene　(TiO2-GR)　have　been　prepared　via　a　facile　hydrothermal　reaction　of　graphene　oxide　and　TiO2　in　an　ethanol-water　solvent.　We　show　that　such　a　TiO2-GR　nanocomposite　exhibits　much　higher　photocatalytic　activity　and　stability　than　bare　TiO2　toward　the　gas-phase　degradation　of　benzene,　a　volatile　aromatic　pollutant　in　air.　By　investigating　the　effect　of　different　addition　ratios　of　graphene　on　the　photocatalytic　activity　of　TiO2-GR　systematically,　we　find　that　the　higher　weight　ratio　in　TiO2-GR　will　decrease　the　photocatalytic　activity.　Analogous　phenomenon　is　also　observed　for　the　liquid-phase　degradation　of　dyes　over　TiO2-GR.　In　addition,　the　key　features　for　TiO2-GR　including　enhancement　of　adsorptivity　of　pollutants,　light　absorption　intensity,　electron-hole　pairs　lifetime,　and　extended　light　absorption　range　have　also　been　found　in　the　composite　of　TiO2　and　carbon　nanotubes　(TiO2-CNT).　These　strongly　manifest　that　TiO2-GR　is　in　essence　the　same　as　other　TiO2-carbon　(carbon　nanotubes,　fullerenes,　and　activated　carbon)　composite　materials　on　enhancement　of　photocatalytic　activity　of　TiO2,　although　graphene　by　itself　has　unique　structural　and　electronic　properties.　Notably,　this　key　fundamental　question　remains　completely　unaddressed　in　a　recent　report　(ACS　Nano　2010,　4,　380)　regarding　liquid-phase　degradation　of　dyes　over　the　TiO2-GR　photocatalyst.　Thus,　we　propose　that　TiO2-GR　cannot　provide　truly　new　insights　into　the　fabrication　of　TiO2-carbon　composite　as　high-performance　photocatalysts.　It　is　hoped　that　our　work　could　avert　the　misleading　message　to　the　readership,　hence　offering　a　valuable　source　of　reference　on　fabricating　TiO2-carbon　composites　for　their　application　as　a　photocatalyst　in　the　environment　cleanup.