Photocatalytic　hydrogen　production　from　water　is　a　promising　strategy　for　the　direct　conversion　of　sunlight　into　chemical　energy,　which　is　considered　as　a　long-term　and　sustainable　solution　to　address　worldwide　energy　and　environmental　issues.　Herein,　we　develop　carbon　doped　boron　nitride　(BCN)　as　metal-free　photocatalysts　by　using　solid-gas　reaction　and　molecular　design　method　of　boron　source.　Four　kinds　of　boron　carbon　nitride　(BCN)　were　synthesized　through　mixed　glucoses　with　melamine　phosphate　borate　(MPB),　melamine　borate　(MB),　boric　acid　(BA)　and　boron　oxide　(BO),　respectively.　It　can　be　found　that　the　morphology　of　BCN-MPB　(nanosheets)　is　different　from　bulk　BCN-MB,　bulk　BCN-BA　and　bulk　BCN-BO.　The　BCN-MPB　nanosheets　show　much　higher　specific　surface　area,　the　longer　lifetime　of　photoexcited　charge　carriers,　and　the　stronger　electron　transport　ability　compared　to　those　of　bulk　BCN.　Thus,　BCN-MPB　nanosheets　exhibit　significantly　improved　photocatalytic　hydrogen　activities　under　visible　light　illumination　compared　to　those　of　bulk　BCN.　Our　work　represents　a　facile　and　template-free　synthesis　strategy　for　the　rational　design　of　eco-friendly,　stable　and　inexpensive　photocatalysts,　and　paves　new　pathways　for　tuning　their　photoreactivity　in　sustainable　light-to-energy　conversion.