Shape-Controlled Metal-Free Catalysts: Facet-Sensitive Catalytic Activity Induced by the Arrangement Pattern of Noncovalent Supramolecular Chains

Abstract

Metal-free catalytic materials have recently received broad attention as promising alternatives to metal-involved catalysts. This is owing to their inherent capability to overcome the inevitable limitations of metal-involved catalysts, such as high sensitivity to poisoning, the limited reserves, high cost and scarcity of metals (especially noble metals), etc. However, the lack of shape-controlled metal-free catalysts with well-defined facets is a formidable bottleneck limiting our understandings on the underlying structure-activity relationship at atomic/molecular level, which thereby restrains their rational design. Here, we report that catalytically active crystals of a porphyrin, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, could be shaped into well-defined cubes and sheet-like tetradecahedrons (TDHD), which are exclusively and predominantly enclosed by {101} and {001} facets, respectively. Fascinatingly, compared to the cubes, the TDHDs display substantially enhanced catalytic activity toward water decontamination under visible-light irradiation, although both the architectures have identical crystalline structure. We disclose that such interesting shape-sensitive catalytic activity is ascribed to the distinct spatial separation efficiency of photogenerated electrons and holes induced by single-channel and multichannel charge transport pathways along noncovalent supramolecular chains, which are arranged as parallel-aligned and 2D network patterns, respectively. Our findings provide an ideal scientific platform to guide the rational design of next-generation metal-free catalysts of desired catalytic performances.

Hybrid Density Functional Theory Study on Structural and Optoelectronic Properties of ZnSe1–xTex for the Photocatalytic Applications

“…In addition, the effective mass of electrons is smaller than that of the holes for all the Te concentration. A large difference between the effective mass of holes and electrons is helpful to suppress the recombination of photogenerated charge carriers . A relatively large variation between the effective mass of holes and electrons is observed at 25% and 50% of Te doping, while a further increase of Te concentration in the ternary alloys reduces this difference.…”

“…A large difference between the effective mass of holes and electrons is helpful to suppress the recombination of photogenerated charge carriers. 50 A relatively large variation between the effective mass of holes and electrons is observed at 25% and 50% of Te doping, while a further increase of Te concentration in the ternary alloys reduces this difference. Moreover, the charge carrier mobility (μ) for ZnSe 1−x Te x is calculated by using ab initio model of Boltzmann transport (aMoBT) equation.…”

Functional Supramolecular Gels Based on the Hierarchical Assembly of Porphyrins and Phthalocyanines

“…Especially, the systems derived from the hierarchical assembly of porphyrins and phthalocyanines are becoming more and more important. For the achievement of so many applications, the cooperative organization of molecular building blocks plays very important role (Guo et al, 2014; Zhao et al, 2014; Zhang et al, 2015; Geng et al, 2017, 2018; Yang et al, 2018c; Chang et al, 2019; Li et al, 2019b). And supramolecular gels with plentiful nanostructures and properties can be good carriers for the fabrication of porphyrin and phthalocyanine assemblies.…”

Tuning the Supramolecular Structures of Metal-Free Porphyrin via Surfactant Assisted Self-Assembly to Enhance Photocatalytic Performance

“…The aggregates not only broaden the light absorption range, but also enhance the stability of the porphyrin photocatalyst due to the geometrical constraints of the rigid frame [14]. Furthermore, the mode of molecules aggregation and morphology of nanostructures are very essential to the separation and transmission of photogenerated charges [15,16]. When the porphyrin is assembled into a crystal structure, higher charge mobility can be obtained, and is an important prerequisite for photocatalytic reactions [17,18,19,20].…”