Transition　metal　doped　ZnO　(TM-ZnO)　nanoparticles　with　3%　dopant　content　are　successfully　prepared　via　a　simple　solvothermal　route.　This　work　highlights　Mn,　Fe,　Co,　Ni　or　Cu　ions　as　the　dopant　transition　metals.　The　as-prepared　samples　are　wurtzite　phase　ZnO　crystals,　and　the　average　sizes　of　undoped　ZnO　and　TM-ZnO　nanoparticles　range　from　200　nm　to　400　nm.　XPS　studies　confirm　that　the　transition　metal　ions　are　successfully　doped　into　the　crystal　lattice　of　ZnO.　The　band　gaps　of　the　undoped　ZnO　and　TM-ZnO　crystals　are　calculated　by　using　UV-DRS　spectroscopic　measurements.　The　visible　light　response　of　ZnO　nanomaterials　is　improved　by　doping　transition　metal　ions.　For　investigating　the　influence　of　transition　metal　doping　on　the　photocatalytic　performance　of　ZnO,　the　photodegradation　rate　of　methylene　blue　(MB)　is　investigated　under　simulated　sunlight　irradiation.　The　photocatalytic　properties　of　ZnO　doped　with　transition　metals　are　improved　at　different　degrees,　among　which　Cu-doped　ZnO　exhibits　the　best　photocatalytic　performance.　Based　on　density　functional　theory　(DFT)　calculation　result,　a　possible　photocatalytic　mechanism　is　proposed.　Furthermore,　the　antibacterial　performance　of　Cu-doped　ZnO　is　investigated　by　selecting　E.　coli,　under　simulated　sunlight　irradiation　and　remarkable　sterilization　of　E.　coli　is　achieved.　©　2019　Elsevier　Ltd　and　Techna　Group　S.r.l.