Size Engineering of Metal–Organic Framework MIL-101(Cr)–Ag Hybrids for Photocatalytic CO₂ Reduction

Abstract

Particle size-tuned photocatalytic activity has been recognized for noble metals such as platinum; however, it is not established for metal−organic frameworks (MOFs). In this work, nanoscaled MOF MIL-101(Cr)−Ag nanoparticle hybrids with varied sizes ranging from 80 to 800 nm have been successfully achieved, and their size effect on photocatalytic CO 2 reduction under visible light has been examined. We show that when the size of MIL-101(Cr)−Ag is reduced to 80 nm, the hybrid catalyst shows the highest CO 2 photocatalytic reduction activity with remarkable production rates of 808.2 μmol/g•h for CO and 427.5 μmol/g•h for CH 4 , representing one of the most efficient hybrid catalysts. The high catalytic activity of the small-sized hybrid catalyst can be ascribed to the high density of unit cells on corners and edges of the catalyst, which are favorable for electron transfer in the photocatalytic CO 2 reduction, supported by a set of complimentary photochemical and electrochemical methods.

MOF‐Based Hybrids for Solar Fuel Production

“…To improve these weak points, combining metal or oxide NPs and carbon‐based materials with MOFs can be an effective solution. [ 126,299 ]…”

“…successfully synthesized hierarchical porous‐structured UiO‐66(Zr) decorated with ultrafine TiO 2 NPs. [ 299b ] The TiO 2 NPs were loaded onto the UiO‐66(Zr) at 81.3 wt% of the MOF. The specific surface area of TiO 2 /UiO‐66(Zr) was as low as 35% of that of pristine UiO‐66(Zr).…”

Rare‐Earth‐Based Metal–Organic Frameworks as Multifunctional Platforms for Catalytic Conversion

“…During the photocatalytic process, metal nodes of MOFs can act as insular semiconductor quantum dots, which can be motivated by the organic linkers or stimulated directly under light illumination. [72,78,79] The light absorption performance of the MOFs is tunable by adjusting the metal nodes and organic ligands.…”

Recent Advances in Photocatalytic CO2 Utilisation Over Multifunctional Metal–Organic Frameworks

“…Through the reduction of an AgNO 3 precursor using NaBH 4 , Guo et al decorated the external surfaces of pre-formed chromium terephthalate metal-organic framework, MIL-101(Cr) (Matérial Institut Lavoisier) nanocrystals with~8 nm Ag NPs [97]. Displaying the characteristic deep-green colour of Cr 3+ , bare MIL-101(Cr) strongly absorbs in the visible region.…”

“…The use of less expensive non-noble-metals [112][113][114] such as Co, Ni, Fe, and Cu in MOF photocatalysts with high catalytic activity and selectivity is still a challenge when developing low-cost materials [15,[96][97][98]. It is highly desired to develop cost-effective materials with high performance and durability [115][116][117], and research efforts have focussed on developing non-noble-metal MOF analogues that rival the catalytic performance of the noble-metal-based counterparts.…”