This　study　was　mainly　aimed　at　constructing　an　amorphous　NiO　modified　g-C　3　N　4　non-noble　metal　heterojunction　photocatalyst　for　enhanced　visible-light　hydrogen　evolution.　The　Ni　species　modified　g-C　3　N　4　sample　was　firstly　prepared　through　the　wetness　impregnation　method　and　then　the　phase　and　crystallinity　of　Ni　species　co-catalysts　on　g-C　3　N　4　were　adjusted　by　the　thermal　oxidation　at　different　temperature.　The　detailed　characterizations　revealed　that　the　amorphous　NiO　co-catalysts　are　supported　successfully　on　g-C　3　N　4　,　and　the　C–O–Ni　linkages　in　the　amorphous　NiO/g-C　3　N　4　heterojunctions　are　formed　at　NiO　and　g-C　3　N　4　interface　after　annealing　at　300　°C.　Compared　to　bare　g-C　3　N　4　and　crystalline　NiO　modified　g-C　3　N　4　photocatalysts,　amorphous　NiO　modified　g-C　3　N　4　non-noble　metal　photocatalyst　showed　significantly　enhanced　visible-light　photocatalytic　hydrogen　production　activity.　The　amorphous　NiO　co-catalysts　provided　more　active　sites　for　H　2　evolution　and　amorphous　NiO　modification　caused　the　enhanced　visible-light　response.　Moreover,　amorphous　NiO/g-C　3　N　4　heterojunctions　formed　at　interface　between　amorphous　NiO　and　host　g-C　3　N　4　created　an　inner　electric　field,　which　allowed　for　the　transfer　of　the　photogenerated　electrons　of　g-C　3　N　4　across　the　interfacial　C–O–Ni　linkages　to　amorphous　NiO　co-catalysts　and　thus　significantly　promoted　the　migration　and　separation　of　photogenerated　charge　carriers.　©　2017　Elsevier　B.V.