How　to　control　the　size　and　dispersity　of　co-catalysts　and　enhance　the　interaction　between　the　catalyst　and　co-catalysts　are　open　issues　in　catalysis.　In　this　work,　we　have　developed　a　novel　approach　to　solve　the　aforementioned　problems　by　utilizing　the　interlayered　spatial　steric　inhibition　effect　of　layered　materials　and　the　self-assembly　of　2D　nanosheets.　A　Ni(OH)2-modified　few-layered　HNb3O8　photocatalyst　is　taken　as　a　typical　example.　SEM　and　TEM　results　show　that　the　co-catalyst　Ni(OH)2　with　an　ultrasmall　size　has　been　uniformly　dispersed　on　the　HNb3O8　layers　through　our　method.　However,　the　samples　prepared　by　a　traditional　deposition　method　exhibit　a　heterogeneous　Ni(OH)2　modification　with　a　large　size.　That　is,　our　method　could　provide　a　larger　number　of　surface　active　sites.　Furthermore,　due　to　the　confined　interlayer　region　of　the　layered　HNb3O8,　a　very　strong　interaction　between　Ni(OH)2　and　HNb3O8　is　achieved.　As　a　result,　the　photogenerated　charge　carriers　have　been　separated　efficiently　and　the　lifetime　of　the　charge　carrier　is　prolonged.　Thus,　the　photocatalytic　activities　of　our　Ni(OH)2/HNb3O8　samples　are　greatly　enhanced.　The　optimal　H2　evolution　rate　of　our　sample　is　about　15.7　times　higher　than　that　of　the　sample　prepared　by　a　traditional　co-catalyst　modification　method.　This　work　highlights　an　efficient　strategy　for　obtaining　a　highly　dispersed　co-catalyst,　which　might　help　to　guide　the　way　toward　the　development　of　highly　efficient　co-catalyst-modified　photocatalyst　systems.　©　2017　The　Royal　Society　of　Chemistry.