%0 Journal Article %T Selective Catalytic Electroreduction of CO2 at Silicon Nanowires (SiNWs) Photocathodes Using Non-Noble Metal-Based Manganese Carbonyl Bipyridyl Molecular Catalysts in Solution and Grafted onto SiNWs %+ Institut des Sciences Chimiques de Rennes (ISCR) %+ Département de Chimie Moléculaire (DCM) %A Torralba-Penalver, Encarnacion %A Luo, Yun %A Compain, Jean-Daniel %A Chardon-Noblat, Sylvie %A Fabre, Bruno %Z ANR-11-LABX-0003-01, Agence Nationale de la Recherche %Z Institut de Chimie Moléculaire de Grenoble %< avec comité de lecture %@ 2155-5435 %J ACS Catalysis %I American Chemical Society %V 5 %N 10 %P 6138–6147 %8 2015 %D 2015 %R 10.1021/acscatal.5b01546 %Z Chemical SciencesJournal articles %X The electrocatalytic redn. of CO2 to CO in hydroorg. medium has been investigated at illuminated (λ \textgreater 600 nm; 20 mW cm-2) hydrogen-terminated silicon nanowires (SiNWs-H) photocathodes using three Mn-based carbonyl bipyridyl complexes as homogeneous mol. catalysts ([Mn(L) (CO)3(CH3CN)](PF6) and [Mn(bpy) (CO)3Br] with L = bpy = 2,2'-bipyridine and dmbpy = 4,4'-dimethyl-2,2'-bipyridine). Systematic comparison of their cyclic voltammetry characteristics with those obtained at flat hydrogen-terminated silicon and traditional glassy carbon electrodes (GCE) enabled us to demonstrate the superior catalytic efficiency of SiNWs-H in terms of cathodic photocurrent densities and overpotentials. For example, the photocurrent densities measured at -1.0 V vs SCE for [Mn(bpy) (CO)3(CH3CN)](PF6) at SiNWs-H exceeded 1.0 mA cm-2 in CO2-satd. CH3CN + 5% vol./vol. H2O, whereas almost zero current was measured at this potential at GCE. Such characteristics have been supported by the energetic diagrams built for the different SiNWs\textbarMn-based catalyst interfaces. The fill factor FF and energy conversion efficiency η calcd. under catalytic conditions were higher for [Mn(bpy or dmbpy) (CO)3(CH3CN)](PF6) (FF = 0.35 and 0.34; η = 3.0 and 2.0%, resp.). Further preparative-scale electrolysis at SiNWs-H photocathode with Mn-based complex catalysts in electrolytic soln. evidenced the quant. conversion of CO2 to CO with a higher stability of the [Mn(dmbpy) (CO)3(CH3CN)](PF6) complex. Finally, in order to develop technol. viable electrocatalytic devices, the elaboration of SiNWs-H photoelectrodes modified with a Mn-based complex has been successfully achieved from an electropolymerizable catalyst, and it was shown that the electrocatalytic activity of the complex was retained after immobilization. %G English %L hal-01208405 %U https://univ-rennes.hal.science/hal-01208405 %~ UNIV-RENNES1 %~ UGA %~ CNRS %~ UNIV-GRENOBLE1 %~ INSA-RENNES %~ ENSC-RENNES %~ IGR %~ ISCR %~ SCR_MACSE %~ DCM %~ STATS-UR1 %~ UR1-SPM %~ INC-CNRS %~ UR1-UFR-SPM %~ UR1-HAL %~ UR1-SDLM %~ UR1-SDLMJONCH %~ TEST-UNIV-RENNES %~ TEST-UR-CSS %~ UNIV-RENNES %~ INSA-GROUPE %~ ANR %~ UR1-MMS %~ TEST2-HALCNRS