Mesoporous　carbon　nitride　(mpg-C3N4)　polymer　can　function　as　a　metal-free　photocatalyst　to　activate　O2　for　the　selective　oxidation　of　benzyl　alcohols　with　visible　light,　avoiding　the　cost,　toxicity,　and　purification　problems　associated　with　corresponding　transition-metal　systems.　By　combining　the　surface　basicity　and　semiconductor　functions　of　mpg-C3N4,　the　photocatalytic　system　can　realize　a　high　catalytic　selectivity　to　generate　benzaldehyde.　The　metal-free　photocatalytic　system　also　selectively　converts　other　alcohol　substrates　to　their　corresponding　aldehydes/ketones,　demonstrating　a　potential　pathway　of　accessing　traditional　mild　radical　chemistry　with　nitroxyl　radicals.　©　2010　American　Chemical　Society.