An　efficient　photocatalytic　CO2　reduction　has　been　reported　in　ZIF-67-derived-Co　nanoparticles　(NPs)　encapsulated　in　nitrogen-doped　carbon　layers　(N-C/Co).　This　work　demonstrates　that　the　pyrolysis　temperature　is　crucial　in　tuning　the　grain　size　and　components　of　metallic　Co-0　of　N-C/Co　composite　catalysts,　which　optimizes　their　photocatalytic　activities.　Syntheses　were　conducted　at　600,　700,　and　800　degrees　C　giving　the　N-C/Co-600,　N-C/Co-700,　and　N-C/Co-800　samples,　respectively.　N-C　layers　can　well　wrap　the　Co　NPs　obtained　at　a　low　pyrolysis　temperature　(600　degrees　C)　owing　to　their　smaller　grains　than　those　of　other　samples.　A　high　metallic　Co-0　content　in　the　N-C/Co-600　sample　can　be　attributed　to　the　effective　inhibition　of　surface　oxidation.　By　contrast,　the　surface　CoOx　oxides　in　the　N-C/Co-700　and　N-C/Co-800　samples　cover　inside　Co　cores,　inhibiting　charge　separation　and　transfer.　As　a　result,　the　N-C/Co-600　sample　yields　the　best　photocatalytic　activity.　The　carbon　monoxide　and　hydrogen　generation　rates　are　as　high　as　1.62　x　10(4)　and　2.01　x　10(4)　mu　mol　g(-1)　h(-1),　respectively.　Additionally,　the　Co　NPs　make　composite　catalysts　magnetic,　enabling　rapid　and　facile　recovery　of　catalysts　with　the　assistance　of　an　external　magnetic　field.　This　work　is　expected　to　provide　an　instructive　guideline　for　designing　metal-organic　framework-derived　carbon/metal　composite　catalysts.