Save multiple raster files as shapefiles

I am trying to reproject multiple raster layers and then save the resultant images as shapefiles. I seem to be getting an error this error – inherits(obj, "Spatial") is not TRUE. Below is the code.

outpath <- "output/path"

setwd("X:/input/patht") 

files <- list.files(pattern=".tif") 

outfiles <- paste0(outpath, files)

for(i in 1:length(files)) {

  r <-raster(files[i])

  newproj <- CRS("+proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 ")

  rWGS <-  projectRaster(r, crs= newproj, res= 0.00012603363)

  rc1 <- writeOGR(rWGS, outfiles[i], driver="ESRI Shapefile", overwrite=TRUE)

}