Sodium Cation Substitution in Sr₂KTa₅O₁₅ toward Enhancement of Photocatalytic Conversion of CO₂ Using H₂O as an Electron Donor

Abstract

The K and Sr cations (K + and Sr 2+ ) in a Sr 2 KTa 5 O 15 photocatalyst were found to be easily substituted by Na cations (Na + ) to form Sr x K y Na z Ta 5 O 15 by a facile one-pot flux method using a mixture of potassium chloride (KCl) and sodium chloride (NaCl). Sr x K y Na z Ta 5 O 15 fabricated using a mixture of KCl and NaCl with a Ag cocatalyst showed enhanced photocatalytic activity without apparent change in selectivity toward CO for the photocatalytic conversion of CO 2 using H 2 O. The present study demonstrates that the flux treatment significantly affected the phase, morphology, band gap, and surface Sr composition of the catalyst owing to the substitution of K + and Sr 2+ for Na + . The stability and durability of the catalyst were also enhanced as compared to those of the photocatalyst fabricated using only KCl flux due to more stable Ag on the surface of Sr x K y Na z Ta 5 O 15 .

Silver-loaded sodium titanate photocatalysts for selective reduction of carbon dioxide to carbon monoxide with water

“…In literature, it was reported that a mixture of two fluxes could enhance the activity of Sr2KTa5O15 photocatalyst [48], which motivated us to fabricate five samples with the different mixing ratio of NaCl and KCl fluxes in this study (Fig. S2).…”

Effective Driving of Ag-Loaded and Al-Doped SrTiO3 under Irradiation at λ > 300 nm for the Photocatalytic Conversion of CO2 by H2O

“…The gaseous products evolved from the photoreaction system (e.g., H 2 , O 2 , and CO) were detected by thermal conductivity detector−gas chromatography (TCD-GC) using a GC-8A chromatograph (Shimadzu Corp.) equipped with a 5 Å molecular sieve column with Ar as the carrier gas and by flame ionization detector−gas chromatography (FID-GC) using a methanizer and a ShinCarbon ST column with N 2 as the carrier gas. In the isotope-labeling experiment, 12 CO 2 gas was replaced with 13 CO 2 . The formation of 13 CO and 12 CO under photoirradiation was analyzed by using a quadrupole-type mass spectrometer (BEL Japan, Inc., BEL Mass) combined with TCD-GC using Ar as the carrier gas.…”

“…The emission of CO 2 as a greenhouse gas is one of the most predominant causes of global warming, , which is known to result in climate change, sea surface elevation, and species extinction. − To address the issues caused by CO 2 , artificial photosynthesis, which is the photocatalytic conversion of CO 2 into chemicals such as carbon monoxide (CO), formic acid (HCOOH), methanol (CH 3 OH), methane (CH 4 ), and other organic chemicals, has been reported to exhibit potential in terms of optimizing the energy structure and achieving energy recycling. ,− As such, numerous studies have focused on the development and design of novel photocatalysts for the reduction of CO 2 , where electron donors such as sacrificial reagents are required due to the redox nature of the photocatalytic reaction. − , For example, water (H 2 O) is the most attractive electron donor due to its substantial reserves on earth, relative cheapness, and nontoxicity. Indeed, our group have reported that Ag-loaded ZnGa 2 O 4 /Ga 2 O 3 , ZnGa 2 O 4 , LaTi 2 O 7 , SrO-modified Ta 2 O 5 , ZnTa 2 O 6 , Sr 2 KTa 5 O 15 , and SrNb 2 O 6 exhibited excellent performances for the photocatalytic conversion of CO 2 using H 2 O as an electron donor. However, the evolution of H 2 rather than CO is preferred when H 2 O is used as the electron donor, since the redox potential of CO 2 /CO (−0.51 V vs NHE, at pH 7) is more negative than that of H + /H 2 (−0.41 V vs NHE, at pH 7) in an aqueous solution .…”

“…2,6−18 As such, numerous studies have focused on the development and design of novel photocatalysts for the reduction of CO 2 , where electron donors such as sacrificial reagents are required due to the redox nature of the photocatalytic reaction. [6][7][8][9][10][11][12][13][14][15][16]19 For example, water (H 2 O) is the most attractive electron donor due to its substantial reserves on earth, relative cheapness, and nontoxicity. Indeed, our group have reported that Ag-loaded ZnGa 2 O 4 /Ga 2 O 3 , 8 ZnGa 2 O 4 , 9 LaTi 2 O 7 , 10 SrO-modified Ta 2 O 5 , 11 ZnTa 2 O 6 , 13 Sr 2 KTa 5 O 15 , 12 and SrNb 2 O 6 15 exhibited excellent performances for the photocatalytic conversion of CO 2 using H 2 O as an electron donor.…”

“…[6][7][8][9][10][11][12][13][14][15][16]19 For example, water (H 2 O) is the most attractive electron donor due to its substantial reserves on earth, relative cheapness, and nontoxicity. Indeed, our group have reported that Ag-loaded ZnGa 2 O 4 /Ga 2 O 3 , 8 ZnGa 2 O 4 , 9 LaTi 2 O 7 , 10 SrO-modified Ta 2 O 5 , 11 ZnTa 2 O 6 , 13 Sr 2 KTa 5 O 15 , 12 and SrNb 2 O 6 15 exhibited excellent performances for the photocatalytic conversion of CO 2 using H 2 O as an electron donor. However, the evolution of H 2 rather than CO is preferred when H 2 O is used as the electron donor, since the redox potential of CO 2 /CO (−0.51 V vs NHE, at pH 7) is more negative than that of H + /H 2 (−0.41 V vs NHE, at pH 7) in an aqueous solution.…”