Photocatalytic hydrogen evolution mechanisms mediated by stereoactive lone pairs of Sb2VO5 in quantum dot heterostructures

Interface-modulated kinetic differentials in electron and hole transfer rates as a key design principle for redox photocatalysis by Sb2VO5/QD heterostructures

“…2,[7][8][9][10][11] Yet, The Journal of Chemical Physics ARTICLE pubs.aip.org/aip/jcp photocatalyst architectures are plagued by low efficiency, poor selectivity, susceptibility to photodegradation, and reliance on a limited palette of materials that are often subject to criticality constraints. 2,[11][12][13] In order to split water into solar fuels, hydrogen and oxygen, photocatalytic architectures must precisely orchestrate a complex sequence of elementary reactions and charge/mass transport processes: (i) Absorption of sunlight, (ii) separation of electrons and holes (typically initiated by photoexcitation across a bandgap transition in a semiconductor) in real space, (iii) transport of charge carriers to sites that can mediate redox catalysis at low overpotentials, (iv) catalysis of redox reactions to yield O 2 and H 2 , and (v) transport of reactants between catalytic sites. [7][8][9]14 Quantum dots (QDs) have long been acknowledged as prime candidates for solar light harvesting since their first discovery, owing to their high oscillator strengths and size-tunable optical and electronic properties.…”

“…14,[28][29][30] In this article, we examine thermodynamic driving forces and excitedstate electron and hole transfer dynamics in SbV 2 O5/CdSe QD heterostructures, a promising new class of photocatalysts that leverage midgap states derived from the stereochemically active 5s 2 lone-pairs of Sb to effect hole extraction from photoexcited II-VI QDs. 13 A broad range of semiconductor heterostructures have been explored with staggered conduction and valence band edges that are amenable to charge separation and the generation of electron-hole pairs upon photoexcitation. 9,23,[25][26][27] A promising design strategy involves interfacing II-VI QDs with transition metal oxides exhibiting mid-gap states derived from the stereochemically active 5/6 s 2 electron lone pairs of p-block cations.…”

“…1(d)]. 13,35 The midgap states of this compound are optimally positioned to facilitate excited-state hole transfer from the valence band edges of photoexcited II-VI QDs. The resulting Sb 2 VO5/QD photocatalysts catalyze both oxidative and reductive half-reactions, including oxygen reduction and hydrogen evolution, in photoelectrochemical cells, as well as in the form of dispersed photocatalysts.…”

“…The resulting Sb 2 VO5/QD photocatalysts catalyze both oxidative and reductive half-reactions, including oxygen reduction and hydrogen evolution, in photoelectrochemical cells, as well as in the form of dispersed photocatalysts. 13 Understanding and manipulating charge transfer kinetics at the interfaces of QDs is integral to advancing their role in redox photocatalysis. Charge transfer processes play a pivotal role in excited state reactivity, wherein they influence both reaction rates and yields.…”

“…1). 13 In the latter approach, cysteine (cys) is used as a molecular linker to tether the QDs to Sb 2 VO5. We specifically sought to understand the role of electron and hole transfer dynamics in mediating the previously reported improved photocatalytic function for LAA-derived heterostructures as compared to SILAR-based heterostructures.…”