Photocatalytic CO2 reduction by Cr-substituted Ba2(In2-Cr )O5·(H2O)  (0.04 ≤ x ≤ 0.60)

Yoon, Songhak; Gaul, Michael D.; Sharma, Sitansh; Son, Kwanghyo; Hagemann, Hans; Ziegenbalg, Dirk; Schwingenschlögl, Udo; Widenmeyer, Marc; Weidenkaff, Anke

doi:10.1016/j.solidstatesciences.2018.02.005

Cited by 5 publications

(4 citation statements)

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“…Thus, we assume H 2 O molecules to be present in a disordered state because of the high dynamism of the system. Still, the presence of H 2 O molecules in the sample gives a plausible explanation to the herein-presented results and the much higher hydrogen content of all chromium-substituted samples (see [2]). However, it has to be pointed out that the so-far performed measurements do not allow to unambiguously distinguish between OH groups and H 2 O in Ba 2 In 1.8 Cr 0.2 O 5.3 (H 2 O) x .…”

Section: Nuclear Magnetic Resonance Spectroscopysupporting

confidence: 62%

“…The brownmillerite-type material Ba 2 In 2 O 5 has already demonstrated striking potential in various applications, ranging from the photocatalytic CO 2 conversion in the presence of H 2 [1][2][3] via oxygen transport membranes [4] to proton conductors [5][6][7][8][9]. The latter is related to the well-known reversible uptake of H 2 O by Ba 2 In 2 O 5 .…”

Section: Introductionmentioning

confidence: 99%

“…The stepwise dehydration and high-temperature phase transition from an orthorhombic brownmillerite-type via a tetragonal intermediate phase to a cubic defect-perovskite-type structure at T > 1300 K create a rich structural variety in the system Ba-In-O [10][11][12][13][14]. The partial replacement of In by Cr forming Ba 2 In 2−x Cr x O 5±δ has shown a massive performance improvement during photocatalytic CO 2 conversion and oxygen transport [2,4]. An important factor responsible for the improvement is that the brownmillerite-type structure favours the oxidation of Cr 3+ to Cr 6+ [15] during preparation in air, hence turning the initially anticipated isovalent doping or substitution into heterovalent doping, causing remarkable structural changes at low and intermediate temperatures [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…1 eV. Hence, providing an enhanced visible light absorption and better conversion efficiency [2]. Besides, the doping effect, the replacement of large In 3+ (r(In 3+ , CN=6) = 0.80 Å) [21] by small Cr 6+ (r(Cr 6+ , CN=6) = 0.44 Å) [21] causes significant structural changes with respect to the unit cell size and oxygen vacancy ordering.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Cr Doping and Water Content on the Crystal Structure Transitions of Ba2In2O5

et al. 2021

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Temperature-dependent crystal structure alterations in the brownmillerite-type material Ba2In2O5 play a fundamental role in its applications: (i) photocatalytic CO2 conversion; (ii) oxygen transport membranes; and (iii) proton conduction. This is connected to a reversible uptake of up an equimolar amount of water. In this study, in situ X-ray and neutron diffraction were combined with Raman spectroscopy and solid-state nuclear magnetic resonance experiments to unravel the effects of Cr doping and water content on the crystal structure transitions of Ba2In2O5(H2O)x over a wide temperature range (10 K ≤ T ≤ 1573 K, x < 1). A mixture of isolated and correlated protons was identified, leading to a highly dynamic situation for the protons. Hence, localisation of the protons by diffraction techniques was not possible. Cr doping led to an overall higher degree of disorder and stabilisation of the tetragonal polymorph, even at 10 K. In contrast, a further disordering at high temperatures, leading to a cubic polymorph, was found at 1123 K. Cr doping in Ba2In2O5 resulted in severe structural changes and provides a powerful way to adjust its physical properties to the respective application.

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Section: Nuclear Magnetic Resonance Spectroscopysupporting

confidence: 62%