Understanding metal–organic frameworks for photocatalytic solar fuel production

Abstract

The fascinating chemical and physical properties of MOFs have recently stimulated exploration of their application for photocatalysis. Despite the intense research effort, the efficiency of most photocatalytic MOFs for solar fuel generation is still very modest. In this highlight we analyse the current status of the field and stress the potential of advanced spectroscopic techniques to gain structural and mechanistic insight and hence support the future development of MOFs to harvest and store solar energy.

Revisiting the Incorporation of Ti(IV) in UiO-type Metal–Organic Frameworks: Metal Exchange versus Grafting and Their Implications on Photocatalysis

“…We propose that use of a more basic Ti salt could deprotonate the defect site and thus enhance grafting of Ti onto the inorganic SBU. Thus, we selected Ti(O n Bu) 4 as the Ti(IV) source for post-synthetic modification of 1 to form a postulated Tigrafted product referred to as 2 (depicted in Figure 1b). Given the reaction conditions, a representative model of the Ti-coordination sphere is likely either octahedral Ti(IV) with either associated hydroxides or alkoxides.…”

“…2 However, most MOFs suffer from hydrolytic instability, limiting their application in aqueous HER photocatalytic systems. 3,4 MOFs of the UiO series possess good water and thermal stability, and opportunities for postsynthetic modification. 5,6 Common strategies for functionalisation of Zr-UiO-type materials include linker modification and metal incorporation.…”

Metal–Organic‐Framework‐Based Catalysts for Photoreduction of CO2

“…[69][70][71][72][73][74] The majority of MOFs show poor electrical conductive behavior owing to their energy-level alignment inadequacy and the symmetry mismatch between ligand orbitals and metal orbitals, resulting in that electrons are not able to transfer in a long-range distance. [85] Photoinduced electrons undergo a short-range electron transfer from an organic linker to its adjacent metal nodes, namely, the linker-to-metal cluster charge transfer (LCCT) (Figure 2a). Additionally, the Fe-O clusters of Fe-containing MOFs can be excited directly, where photoinduced electrons transfer from negative bridging oxygen atoms to positive metal ions (Figure 2b).…”

Chemical Engineering of Photoactivity in Heterometallic Titanium–Organic Frameworks by Metal Doping

“…MOFs featuring LMCTs like MIL‐125 are arguably preferable for photocatalytic purposes due to more efficient charge separation if compared to other systems in which photoexcitation only affects isolated linkers or metals . Also, MUV‐10(Ca) displays excellent chemical stability key to circumvent the drastic conditions often used in photocatalytic experiments.…”