Hollow　carbon　nitride　spheres　with　a　well-designed　architecture　and　excellent　optical　properties　serve　as　promising　polymers　for　solar　fuel　production.　In　this　study,　carbon-rich　hollow　carbon　nitride　nanospheres　were　rationally　designed　for　photocatalytic　hydrogen　peroxide　production.　Experimental　results　revealed　that　the　doping　of　carbon　species　in　the　heptazine　unit　enhanced　light　absorption　and　promoted　charge　separation　and　transport.　Accordingly,　the　optimized　carbon-rich　hollow　carbon　nitride　nanospheres　exhibited　significantly　enhanced　photocatalytic　performance　for　solar-driven　hydrogen　peroxide　production　and　Cr(vi)　reduction　in　comparison　with　pristine　polymeric　carbon　nitride　and　hollow　carbon　nitride　nanospheres.　©　2025　The　Royal　Society　of　Chemistry.