The composite structure of mixed τ-(Ag, Cu) V2O5 bronzes—Evidence for T dependant guest-species ordering and mobility

Hermes, Wilfred; Dollé, Mickaël; Rozier, Patrick; Lidin, Sven

doi:10.1016/j.jssc.2012.11.029

Cited by 2 publications

(1 citation statement)

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“…A further method for adjusting the electronic character of lone-pair V 2 O 5 bronzes, namely, cointercalating multiple cations with highly selective site preferences, has recently been developed and is a direct result of the plethora of insertion sites available in the ζ-V 2 O 5 tunnel. While a disordered layered "quaternary" τ-(Ag,Cu) 0.92 V 2 O 5 bronze has been investigated previously, 68 the deliberate cointercalation of site-selective cations within tunnel-type V 2 O 5 bronzes represents a new and entirely unexplored vector for electronic structure modulation. This approach presents combinatorial opportunities for siteselective cation mixing and valence band engineering in the solid state, with a wide range of structures accessible by diverse synthetic routes.…”

Section: Lone-pair-derived Electronic States and Photocatalysismentioning

confidence: 99%

Lone but Not Alone: Precise Positioning of Lone Pairs for the Design of Photocatalytic Architectures

et al. 2022

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With current economic growth and consumption trends projected to bring about a precipitous and rapid rise of the global temperature, the world stands at a crossroads with regards to climate change. The rate at which greenhouse gas emissions from fossil fuels, industry, and land-use is curtailed over the next decade will determine the trajectory of global warming for the rest of the century. It is increasingly apparent that far-reaching decarbonization of the transportation infrastructure will need to be supplemented by extensive carbon capture, storage, and utilization. Taking a leaf from Nature's playbook, photocatalytic architectures that can utilize water or CO 2 in conjunction with energy harvested from sunlight and store it in the form of energy-dense chemical bonds represent an attractive proposition. Harnessing solar irradiance, through solar energy conversion involving photovoltaics, as well as the photocatalytic generation of solar fuels, and the photocatalytic reduction of CO 2 have emerged as urgent imperatives for the energy transition. Functional photocatalysts must be capable of efficiently absorbing sunlight, effectively separating electronhole pairs, and ensuring they are delivered at appropriate potentials to catalytic sites to mediate redox reactions. Such photocatalytic architectures must further direct redox events down specific pathways to yield desired products, and ensure the transport of reactants between catalytic sites; all with high efficiency and minimal degradation. In this Perspective, we describe a palette of heterostructures designed to promote robust and efficient direct solar-driven water splitting and CO 2 reduction. The heterostructures comprise M x V 2 O 5 or M x M y ′V 2 O 5 , where M is a p-block cation, M′ is an s-, p-, or d-block cation, and V 2 O 5 represents one of multiple polymorphs of this composition interfaced with semiconductor quantum dots (QDs, binary or ternary II−VI or III−V QDs). The stereochemically active 5/6s 2 electron lone pairs of p-block cations in M x V 2 O 5 give rise to filled midgap electronic states that reside above the O 2p-derived valence band. Within heterostructures, the photoexcitation of QDs results in the transfer of holes to the midgap states of M x V 2 O 5 or M x M y ′V 2 O 5 on subpicosecond time scales. Ultrafast charge separation minimizes the photoanodic corrosion of QDs, which has historically been a major impediment to their use in photocatalysis, and enables charge transport and the subsequent redox reactions underpinning photocatalysis to compete with electron−hole recombination. The energy positioning and dispersion of lone pair states is tunable through multiple chemical and compositional levers accessible across the palette of M x V 2 O 5 or M x M y ′V 2 O 5 compounds: choice of lone-pair cation M and its stoichiometry x, atomic connectivity of V 2 O 5 polymorphs, cointercalation of M′ cations in "quaternary" vanadium oxide bronzes, anionic substitution, and alternative lone pair vanadate frameworks with altogether different c...

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Section: Lone-pair-derived Electronic States and Photocatalysismentioning

confidence: 99%