_applied_  
_sciences_  
_Article_  
**Work Function Tuning in Hydrothermally Synthesized**  
**Vanadium-Doped MoO\({}_{3}\) and Co\({}_{3}\)O\({}_{4}\) Mesostructures for Energy Conversion Devices**  
**[PERSON] \({}^{1,2,\ddagger}\), [PERSON] \({}^{1,3,\ddagger}\), [PERSON] \({}^{1}\)\({}^{\copyright}\), [PERSON] \({}^{1}\)\({}^{\copyright}\), [PERSON] \({}^{4}\)\({}^{\copyright}\), [PERSON] \({}^{5}\), [PERSON] \({}^{4}\)\({}^{\copyright}\), [PERSON] \({}^{1,2,6,\ast}\), [PERSON] \({}^{3,7,\ast}\)\({}^{\copyright}\) and [PERSON] \({}^{1,2,\ast}\)\({}^{\copyright}\)**  
\({}^{1}\) Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; [EMAIL_ADDRESS] (P.D.E. ); [EMAIL_ADDRESS] (M.C. ); [EMAIL_ADDRESS] (F.B. ); [PERSON](F.T)  
\({}^{2}\) Interdepartmental Centre Giorgio Levi Cases for Energy Economics and Technology, University of Padova, Via Marzolo 9, 35131 Padova, Italy  
\({}^{3}\) Institute of Physical Chemistry, Justus Liebig University Giessen, 35390 Giessen, Germany  
\({}^{4}\) Materials Characterization Facility, Italian Institute of Technology, Via Morego 30, 16163 Genova, Italy; marco.salerno@itit. (M.S. ); mirko.pato@itit (M.P.) \({}^{5}\) Nanohemistry, Italian Institute of Technology, Via Morego 30, 16163 Genova, Italy; [EMAIL_ADDRESS]  
\({}^{6}\) Karlsruher Institut fur Technologie (KIT), Institut fur Technische Chemie und Polymerchemie (ITCP), 76131 Karlsruhe, Germany  
\({}^{7}\) Center for Materials Research, Justus Liebig University Giessen, 35390 Giessen, Germany  
\({}^{8}\) Correspondence: [EMAIL_ADDRESS] (S.G.); [PERSON]SS] (T.G. ); [EMAIL_ADDRESS] (EL.) \({}^{\dagger}\) These two authors contributed equally. **Clication: [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON], [PERSON]; [PERSON]; [PERSON] Work Function Tuning in Hydrothermally Synthesized**  
\({}^{1}\) Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; [PERSON](P.D.E. ); [PERSON]S] (M.C. ); [PERSON] (F.B. ); [PERSON](F.T)  
\({}^{2}\) Interdepartmental Centre Giorgio Levi Cases for Energy Economics and Technology, University of Padova, Via Marzolo 9, 35131 Padova, Italy  
\({}^{3}\) Institute of Physical Chemistry, Justus Liebig University Giessen, 35390 Giessen, Germany  
\({}^{4}\) Materials Characterization Facility, Italian Institute of Technology, Via Morego 30, 16163 Genova, Italy; marco.salerno@itit. (M.S. ); mirko.pato@itit (M.P.) \({}^{5}\) Nanohemistry, Italian Institute of Technology, Via Morego 30, 16163 Genova, Italy; [EMAIL_ADDRESS]  
\({}^{6}\) Karlsruher Institut fur Technologie (KIT), Institut fur Technische Chemie und Polymerchemie (ITCP), 76131 Karlsruhe, Germany  
\({}^{7}\) Center for Materials Research, Justus Liebig University Giessen, 35390 Giessen, Germany  
\({}^{8}\) Correspondence: [EMAIL_ADDRESS] (S.G.); [EMAIL_ADDRESS] (T.G. ); [EMAIL_ADDRESS] (EL.) \({}^{\dagger}\) These two authors contributed equally. **Abstract:** The wide interest in developing green energy technologies stimulates the scientific community to seek, for devices, new substitute material platforms with a low environmental impact, ease of production and processing and long-term stability. The synthesis of metal oxide (MO) semiconductors fulfils these requirements and efforts are addressed towards optimizing their functional properties through the improvement of charge mobility or energy level alignment. Two MOs have rising perspectives for application in light harvesting devices, mainly for the role of charge selective layers but also as light absorbers, namely MoO\({}_{3}\) (an electron blocking layer) and Co\({}_{3}\)O\({}_{4}\) (a small band gap semiconductor). The need to achieve better charge transport has prompted us to explore strategies for the doping of MoO\({}_{3}\) and Co\({}_{3}\)O\({}_{4}\) with vanadium (V) ions that, when combined with oxygen in V\({}_{2}\)O\({}_{5}\), produce a high work function MO.