Surface-enhanced　Raman　spectroscopy　(SERS)　is　an　ultra-sensitive　and　rapid　technique　that　is　able　to　significantly　enhance　the　Raman　signals　of　analytes　absorbed　on　functional　substrates　by　orders　of　magnitude.　Recently,　semiconductor-based　SERS　substrates　have　shown　rapid　progress　due　to　their　great　cost-effectiveness,　stability　and　biocompatibility.　In　this　work,　three　types　of　faceted　Co3O4　microcrystals　with　dominantly　exposed　{100}　facets,　{111}　facets　and　co-exposed　{100}-{111}　facets　(denoted　as　C-100,　C-111　and　C-both,　respectively)　are　utilized　as　SERS　substrates　to　detect　the　rhodamine　6G　(R6G)　molecule　and　nucleic　acids　(adenine　and　cytosine).　C-100　exhibited　the　highest　SERS　sensitivity　among　these　samples,　and　the　lowest　detection　limits　(LODs)　to　R6G　and　adenine　can　reach　10(-7)　M.　First-principles　density　functional　theory　(DFT)　simulations　further　unveiled　a　stronger　photoinduced　charge　transfer　(PICT)　in　C-100　than　in　C-111.　This　work　provides　new　insights　into　the　facet-dependent　SERS　for　semiconductor　materials.