Huan DOAN, PhD MRSC MInstP
EPSRC Doctoral Prize Fellow
Co-Chair, STEM BAME Staff Network
I am currently an EPSRC Doctoral Prize Fellow at the University of Bristol. I hold a BSc and an MSc in Chemical Engineering (2009 and 2012, Hanoi University of Mining and Geology, Vietnam), an MRes in Sustainable Chemical Technologies (2015, University of Bath, UK) and a PhD in Mechanical Engineering (2019, University of Bristol, UK).
I am working on the synthesis and characterisation of porous materials (metal-organic frameworks, zeolites and functional silicas) to address challenges in sustainable development (catalysis, gas separation and energy storage).
I have demonstrated the impact of my research through participation in a diverse range of outreach activities to raise public awareness and foster industrial collaboration. I have reached the semi-finals of the 3-Minute Thesis competition (2017) at the University of Bristol, and selected to present my work to MPs at Westminster in the prestigious STEM for BRITAIN (2019). My research contributions to the University of Bristol and the wider community have been recognised by being named an Inspirational Bristol Scientist Award in 2019 and an Honourable Mention Award at the UK-wide Doctoral Researcher Award competition in 2020. I am currently the Co-Chair, STEM BAME Staff Network at the University of Bristol; my role is to promote racial equity within science and engineering faculties.
MY CURRENT RESEARCH
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.
Introducing hierarchical pore structure to microporous materials such as metal-organic frameworks (MOFs) can be beneficial for reactions where the rate of reaction is limited by low rates of diffusion or high pressure drop. This advantageous pore structure can be obtained by defect formation, mostly via post-synthetic acid etching, which has been studied extensively on water-stable MOFs. Here we show that a water-unstable HKUST-1 MOF can also be modified in a corresponding manner by using phosphoric acid as a size-selective etching agent and a mixture of dimethyl sulfoxide and methanol as a dilute solvent.
Interestingly, we demonstrate that the etching process which is time- and acidity- dependent, can result in formation of defective HKUST-1 with extra interconnected hexagonal macropores without compromising on the bulk crystallinity. These findings suggest an intelligent scalable synthetic method for formation of hierarchical porosity in MOFs that are prone to hydrolysis, for improved molecular accessibility and diffusion for catalysis.
This work concerns the rapid synthesis of an archetypical metal-organic framework (MOF) material (HKUST-1) whereby the addition of supercritical CO2. The advantages of this method are that it allows a drastic reduction in the amounts of conventional solvents required for synthesis whilst removing the need for a separate post-synthetic solvent removal step and affording control over macroporosity in the resulting crystallites.