Selective Formic Acid Production via CO₂ Reduction with Visible Light Using a Hybrid of a Perovskite Tantalum Oxynitride and a Binuclear Ruthenium(II) Complex

Abstract

A hybrid material consisting of CaTaO2N (a perovskite oxynitride semiconductor having a band gap of 2.5 eV) and a binuclear Ru(II) complex photocatalytically produced HCOOH via CO2 reduction with high selectivity (>99%) under visible light (λ>400 nm). Results of photocatalytic reactions, spectroscopic measurements, and electron microscopy observations indicated that the reaction was driven according to a two-step photoexcitation of CaTaO2N and the Ru photosensitizer unit, where Ag nanoparticles loaded on CaTaO2N with optimal distribution mediated interfacial electron transfer due to reductive quenching.

Activation of the Carbon Nitride Surface by Silica in a CO‐Evolving Hybrid Photocatalyst

“…For the development of artificial photosynthetic schemes, variousm etal complexes [1][2][3][4][5][6][7][8][9][10][11][12][13] and semiconductors, [14][15][16][17][18][19] as well as their hybrids, [20][21][22][23][24][25][26][27][28] have been examined as photocatalystsf or CO 2 reduction. For the development of artificial photosynthetic schemes, variousm etal complexes [1][2][3][4][5][6][7][8][9][10][11][12][13] and semiconductors, [14][15][16][17][18][19] as well as their hybrids, [20][21][22]…”

Undoped Layered Perovskite Oxynitride Li2LaTa2O6N for Photocatalytic CO2 Reduction with Visible Light

“…[22] Thus,weinitially performed CO 2 reduction under 13 CO 2 atmosphere,a nd collected No-D 1 H-NMR spectra to verify the carbon source of formate.U nfortunately,t he low activity/sensitivity of No-D NMR method did not allow the detection of any signal of products from RuRu' '/Li 2 LaTa 2 O 6 N. Accordingly,n anoparticulate Ag (1.5 wt %) was in prior deposited on Li 2 LaTa 2 O 6 Nt op romote CO 2 reduction, as reported previously. [10,11] Deposition of metallic Ag nanoparticles with 20-30 nm in size on Li 2 LaTa 2 O 6 Nw as confirmed by means of XAFS and TEM observations (Supporting Information, Figures S11 and S12). This modification improved the formate production rate (entry 5, Table 1).…”

“…We previously reported that prior modification of CaTaO 2 Nw ith Ag nanoparticles improved the formate production in the visible-light Z-scheme CO 2 reduction with RuRu' '. [10] However,e ven without modification of Ag, the activity of RuRu' '/ Li 2 LaTa 2 O 6 Nw as two-fold higher than that of the optimized RuRu' '/Ag/CaTaO 2 N( entry 8). These results clearly indicate great potentials of layered oxynitride materials as ap hotocatalyst.…”

“…[10] Thec ombined system, RuRu' '/semiconductor, works as follows;b oth semiconductor and metal complex are excited by visible light. Holes in the valence band of the semiconductor oxidize an electron donor and the electron in conduction band reductively quenches the excited state of the photosensitizer unit of RuRu' ',p roducing one electron reduced species (OERS) of the photosensitizer unit.…”

“…This modification improved the formate production rate (entry 5, Table 1). After 15 hirradiation, aclear doublet signal (J 13 CH = 174 Hz) assignable to 13 Co ff ormate [10,11] was observed between 8.54 and 8.05 ppm in the 1 H-NMR spectrum, while only singlet signal derived from H 12 COOH appeared when 12 CO 2 was used (Supporting Information, Figure S13). Thep resent results provide firm evidence that RuRu' '/Ag/Li 2 LaTa 2 O 6 N reduced CO 2 to formate.…”