Efficient　charge　separation　is　one　of　the　critical　issues　for　the　design　of　photocatalytic　systems.　The　physical　mixing　of　photocatalysts　and　cocatalysts　to　prepare　photocatalytic　systems　usually　leads　to　a　high　interfacial　resistance,　which　is　not　beneficial　to　efficient　charge　separation.　Here,　we　report　the　in　situ　construction　of　photocatalytic　systems　by　directly　growing　CdS　nanosheets　on　porous　carbon　aerogels　(CA)　to　obtain　photocatalytic　systems　with　compact　interfacial　contact.　The　photocatalytic　H2　yield　of　the　optimized　CdS@CA　composite　is　∼27.3　mmol/g,　obviously　higher　than　that　of　CdS　nanosheets　(∼11.4　mmol/g).　Electrochemical　and　spectroscopic　methods　demonstrate　that　the　incorporation　of　carbon　aerogels　with　CdS　nanosheets　can　efficiently　inhibit　the　recombination　of　photo-generated　electrons　and　holes,　thus　achieving　highly　improved　photocatalytic　H2　production.　©　2023　American　Chemical　Society