Photocatalytic　reactive　oxygen　species　(ROS)-induced　reactions　provide　an　appealing　method　to　solve　the　environmental　and　energy　issues,　whereas　the　current　oxidation　reaction　generally　suffered　from　low　efficiency　and　poor　selectivity　due　to　uncontrollable　O2　activation　process.　In　view　of　the　existence　of　competitive　electron　and　energy　transfer　pathway,　we　propose　that　highly　efficient　superoxide　radical　anion　(·O2−)　generation　can　be　achieved　by　optimizing　the　order　degree　of　the　photocatalyst.　Herein,　by　taking　carbon　nitride　polymer　as　an　example,　we　optimized　the　crystallization　process　of　carbon　nitride　polymer　by　selecting　precursors　of　different　polymerization　degrees　with　a　molten　salt　method.　Benefiting　from　the　high　crystallinity,　extended　π-conjugated　system　and　strong　van　der-Waals　interactions　between　interlayers,　the　modified　carbon　nitride　polymer　exhibited　accelerated　charge　transport　and　enhancement　in　electron　induced　molecular　oxygen　activation　reactions　under　visible　light.　Consequently,　the　CCN-P　exhibits　about　1.5　times　higher　conversion　rate　in　hydroxylation　of　phenylboronic　acid　and　over　6-fold　faster　degradation　rate　in　Rh　B　organic　pollutants　photodegradation　with　respect　to　pristine　carbon　nitride.　This　study　provides　an　in-depth　understanding　on　the　optimization　of　the　O2　activation　process　and　the　design　of　advanced　photocatalysts.　©　2020　Elsevier　Inc.