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RESEARCH SUMMARY

My goal is to apply sustainable synthesis and advanced manufacturing techniques in the development of a new, cost-effective catalyst with superior performance for environmental remediation, utilising nanoporous materials. Through this work, I aim to address pressing global challenges and support the United Nations' Sustainable Development Goals, with a focus on achieving clean energy (Goal 7), reducing plastic waste (Goal 12), and mitigating global warming (Goal 13).

Main Research Areas:

  • Porous materials synthesis and characterisation

  • Synthesis of hierarchical porous materials using green and scalable synthetic approaches

  • Innovative catalyst technologies using functional porous materials 

  • Energy conversion and storage using hierarchical porous materials

research summary

One of my key scientific contributions was the development of a low-solvent, more environmentally-friendly synthesis route for the production of copper-based MOF catalysts with hierarchical porosity. I have developed a new method using supercritical CO2 (scCO2) as a time- and material-efficient route to MOF synthesis with a high level of control over the crystallization process for accessing tailored material properties. I also made significant intellectual contributions to the development of intelligent scalable synthetic methods to produce additional large pores in defective MOF structures which were shown to be highly beneficial for their catalytic activity. The impact of this approach on heterogeneous catalysis was that these new MOFs with hierarchical porosity delivered an enhanced performance with fast intercalation of reactants into active sites. 

Furthermore, my experience in using sustainable synthetic approaches has allowed me to achieve the economical production of nanomaterials. For instance, I have demonstrated the development of nanocomposites with novel heterostructures using cheap resources such as plastic waste and natural halloysite, for example, producing multifunctional AgInS2@MIL-101(Cr) and O-g-C3N4@MIL-53(Fe) materials with enhanced porosity via a facile preparation, Co-Fe-BTC/CN nanocomposite with bimetallic structures via a microwave-assisted hydrothermal method and Ag@AgBr/Al-SBA-15, Ag-g-C3N4@HNT and V2O5/Al-SBA-15 with semiconductor-containing porous structures via a one-pot and green synthetic approach. The novel nanocomposites were shown to improve the activity of visible-light-driven catalysts for the efficient treatment of multiple toxic pollutants in water. This could allow wastes to be transformed into economically valuable materials again and protect wildlife and the environment from further pollution. 

RESEARCH BLOGS

Introducing heterostructure to graphitic carbon nitrides (g-C3N4) can improve the activity of visible-light-driven catalysts for efficient treatment of multiple toxic pollutants in water. Here we report for the first time that a complex material can be constructed from an oxygen-doped g-C3N4 and MIL-53(Fe) metal-organic framework using a facile hydrothermal synthesis and recycled polyethylene terephthalate from plastic waste. The novel multi-walled nanotube structure of the O-g-C3N4/MIL-53(Fe) composite which enables unique interfacial charge transfer at the heterojunction showed an obvious enhancement in separation efficiency of the photochemical electron-hole pairs. This resulted in narrow bandgap energy (2.30 eV compared to 2.55 eV in O-g-C3N4), high photocurrent intensity (0.17 mA cm-2 compared to 0.12 mA cm-2 and 0.09 mA cm-2 in MIL-53(Fe) and O-g-C3N4, respectively), and excellent catalytic performance in the photodegradation of anionic azo dyes (95% RR 195 and 99% RY 145 degraded after 4 h, and only a minor change in the efficiency observed after four consecutive tests). These results demonstrate the development of new catalysts made from waste feedstocks that show high stability, ease of fabrication and can operate in natural light for environmental remediation.




This work has been published in Faraday Discussions

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photocatalytic oxidative desulfurization

In recent decades, highly efficient deep desulfurization processes have become very necessary to decrease environmental pollution due to sulfur emissions from fuels. Herein, an enhanced photocatalytic desulfurization of a model fuel was investigated under sunlight irradiation using H2O2 as the oxidant and Ag@AgBr loaded mesoporous silica Al-SBA-15 as a catalyst. In this study, the photocatalyst (Ag@AgBr/Al-SBA-15) was synthesized via a chemical deposition using halloysite clay as the silica-aluminum source and characterized by X-ray diffraction (XRD), N2 adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The UV-Vis DRS results revealed that the light absorption expanded to the visible region (λ > 400 nm) for the various Ag@AgBr nanoparticles doped in the mesoporous Al-SBA-15 material. The 30% Ag@AgBr/Al-SBA-15 sample with a 30% Ag@AgBr doping exhibited enhanced photocatalytic activity and showed high stability even after four successive cycles. The results demonstrated that initial dibenzothiophene (DBT) concentrations (500 ppm) reached 98.66% removal with 50 mg of the catalyst dosage, 1.0 mL of H2O2, for 360 min of sunlight irradiation at 70 °C.



XRD Ag@AgBr/Al-SBA-15

Fig 1. (A) Small-angle and (B) wide-angle of XRD patterns of 10%-60%Ag@AgBr/Al-SBA-15 samples



photoluminescence Ag@AgBr/Al-SBA-15

Fig 2. (A) N2 adsorption-desorption isotherms, and (B) pore size distribution of Al-SBA-15 and 10%-60%Ag@AgBr/Al-SBA-15 samples. (C) Room temperature photoluminescence (PL) spectra of 10-60%Ag@AgBr/Al-SBA-15 samples



DBT photodegradation using Ag@AgBr/Al-SBA-15

Fig 3. Photodegradation of DBT with different photocatalyst contents under sunlight irradiation at reaction temperatures of (A) 70 °C and (B) 50 °C. (Reaction conditions: Vmodel oil = 50 mL, mcatalyst = 50 mg, VH2O2 = 1.0 mL)



DBT photodegradation using Ag@AgBr/Al-SBA-15

Fig 4. (A) Photodegradation of DBT by 30%Ag@AgBr/Al-SBA-15 catalyst at different temperatures under sunlight irradiation. (Reaction conditions: Vmodel oil = 50 mL, mcatalyst = 50 mg, VH2O2 = 1.0 mL). (B) Photodegradation of DBT by 30%Ag@AgBr/Al-SBA-15 catalyst at different amount of catalyst under sunlight irradiation. (Reaction conditions: Vmodel oil=50 mL, VH2O2=1.0 mL, reaction temperature of 70 °C)



DBT photodegradation using Ag@AgBr/Al-SBA-15

Fig 5. Plot of (A) pseudo first-order and (B) pseudo second-order kinetic models for the degradation of DBT by photocatalytic oxidative desulfurization at different temperatures



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macroporous MOF

Introducing additional meso- or macroporosity into traditionally microporous metal-organic frameworks (MOFs) is a very promising way to improve the catalytic performance of these materials, mostly due to the resultant reductions of diffusional barriers during reactions. Here we show that HKUST-1 can be successfully synthesised either via post-synthetic treatment (by acid-etching prepared HKUST-1 samples in phosphoric acid, referred to here as “HKUST AE”) or via in situ crystallisation (by exposing the MOF precursor solution to supercritical CO2, referred to here as “HKUST CO2”) to produce hierarchically porous structures that are highly beneficial for catalysis. These hierarchical MOFs were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and gas sorption to confirm the preservation of the microporous structure and the appearance of macropores in the crystallites. More importantly, the benefits of introducing a hierarchical porous structure into this MOF for improving the diffusion accessibility of reagents to the sample in catalysed liquid- and gas-phase reactions were quantified for the first time. It was found that the hierarchical pore structure helped to improve the catalytic performance in CO oxidation, which is evidenced by the greater extent of the reaction over HKUST CO2 compared to the commercial HKUST-1 sample over the same time period, at temperatures between 220 and 260 oC. The hierarchical porous structure proved even more beneficial in liquid phase reactions where more bulky molecules were involved; here the conversion of styrene oxide in methanolysis was used as an example. These findings serve to demonstrate the advantages of using such hierarchical porous MOFs in catalysis.

MOF for catalysis

Figure. Results of CO oxidative reactions (a) and styrene oxide methanolysis reactions (b), showing an improvement in activity for the hierarchical porous MOF (red squares), compared to the normal microporous MOF (yellow triangles)

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