Broadening　the　visible　light　absorption　range　and　accelerating　the　separation　and　migration　process　of　charge　carriers　are　effective　ways　to　improve　photocatalytic　quantum　efficiencies.　In　this　study,　we　show　that　poly　heptazine　imides　with　enhanced　optical　absorption　and　promoted　charge　carrier　separation　and　migration　could　be　obtained　by　means　of　a　rational　design　of　the　band　structures　and　crystallinity　of　polymeric　carbon　nitride.　Copolymerization　of　urea　with　monomers　such　as　2-aminothiophene-3-carbonitrile　would　first　generate　amorphous　melon　with　enhanced　optical　absorption,　while　further　ionothermal　treatment　of　melon　in　eutectic　salts　would　increase　the　polymerization　degree　and　create　condensed　poly　heptazine　imides　as　final　products.　Accordingly,　the　optimized　poly　heptazine　imide　presents　an　apparent　quantum　yield　of　12　%　at　420　nm　for　photocatalytic　hydrogen　production.　©　2023　Wiley-VCH　GmbH.