PhD Student, Monash University Malaysia
My research mainly focuses on photocatalytic CO2 reduction into energy-rich hydrocarbon fuels.
Over the past few decades, blooming of human population and increase of life quality have led to large-scale burning of fossil fuels to meet the global energy demand. As a result, the non-renewable energy source is experiencing rapid depletion, along with massive CO2 greenhouse gas emissions to the atmosphere. In the light of this, incessant research efforts have been devoted to addressing these global energy and environmental issues. Among all the existing approaches, photocatalytic CO2 reduction is deemed as the most sustainable and promising avenue as these notorious CO2 molecules can be transformed back into energy-rich hydrocarbon fuels with solar light as the only energy input. Thus, this process is reputed as reverse combustion or artificial photosynthesis. Nonetheless, the state-of-the-art advances is still far from being industrialized as most of the existing photocatalysts are only responsive to UV and/or visible light, which constitute for only <5% and ~45% of solar spectrum, respectively. The harnessing of near-infrared (NIR) region (~50% of solar light), is highly desirable but challenging owing to its low-photonic energy.
Very recently, I have successfully realized photocatalytic CO2 reduction over full spectrum – from UV to NIR region through surface defect engineering of bismuth tungstate (Bi2WO6). This was incredibly achieved without involving any expensive noble metals or co-catalysts. As far as I know, this is the first research work in Malaysia which demonstrated NIR-driven CO2 reduction, and also the first study in the world that reports on CO2 reduction over UV-Vis-NIR light. Following my first success, I have further developed CQDs-decorated ultrathin Bi2WO6 nanosheets for enhanced photocatalytic performance. My current research focuses on designing novel advanced nanomaterials through strategic coupling, crystal facet engineering and surface defect engineering for achieving superior CO2 reduction photoactivity, with an aim of alleviating environmental issues and imminent energy crisis concurrently.
Abstract: Photocatalytic CO2 reduction over the UV-Vis-NIR broad spectrum was realized for the first time. The presence of surface oxygen vacancy defects on Bi2WO6 resulted in significant photocatalytic enhancement over the pristine counterpart under UV and visible light irradiation. Meanwhile, the photocatalytic responsiveness of Bi2WO6-OV was successfully extended to the NIR region.
Pub.: 23 Nov '16, Pinned: 30 Jun '18
Abstract: A highly facile one-pot ethylene glycol-assisted solvothermal process was employed to fabricate bismuth oxybromide (BiOBr) with oxygen-deficient defects. These defects played an indispensable role for superior photocatalytic CO2 reduction, in which the as-prepared sample demonstrated a remarkable improvement of 3.3 and 5.7-fold for CH4 production over pristine BiOBr and P25, respectively. The enhancement could be attributed to the presence of oxygen vacancies, which acted as the active sites for CO2 adsorption and activation. In addition, the oxygen–deficiency–induced defect states could effectively trap photogenerated electrons, thus improving the separation of the electron–hole pairs and significantly slow down the recombination rate of charge carriers. On top of that, oxygen-deficient BiOBr exhibited long term stability (>50 hours of catalytic reaction) for CO2 photoreduction under simulated solar light, where no reducing agent or any post-treatment was needed to regenerate the oxygen vacancies.
Pub.: 06 Sep '16, Pinned: 30 Jun '18
Abstract: A facile and dopant-free strategy was employed to fabricate oxygen-rich TiO2 (O2-TiO2) with enhanced visible light photoactivity. Such properties were achieved by the in situ generation of oxygen through the thermal decomposition of the peroxo-titania complex. The O2-TiO2 photocatalyst exhibited high photoactivity towards CO2 reduction under visible light.
Pub.: 21 May '14, Pinned: 30 Jun '18
Abstract: Graphene quantum dot (GQD), which is the latest addition to the nanocarbon material family, promises a wide spectrum of applications. Herein, we demonstrate two different functionalization strategies to systematically tailor the bandgap structures of GQDs whereby making them snugly suitable for particular applications. Furthermore, the functionalized GQDs with a narrow bandgap and intramolecular Z-scheme structure are employed as the efficient photocatalysts for water splitting and carbon dioxide reduction under visible light. The underlying mechanisms of our observations are studied and discussed.
Pub.: 17 Mar '18, Pinned: 30 Jun '18
Abstract: BIF-20, a zeolite-like porous boron imidazolate framework with high density of exposed B–H bonding, is combined with graphitic carbon nitride (g-C3N4) nanosheets via a facile electrostatic self-assembly approach under room temperature, forming an elegant composite BIF-20@g-C3N4 nanosheet. The as-constructed composite preferably captures CO2 and further photoreduces CO2 in high efficiency. The photogenerated excitations from the carbon nitride nanosheet can directionally migrate to B–H bonding, which effectively suppresses electron–hole pair recombination and thus greatly improves the photocatalytic ability. Compared to the g-C3N4 nanosheet, the BIF-20@g-C3N4 nanosheet composite displayed a much-enhanced photocatalytic CO2 reduction activity, which is equal to 9.7-fold enhancements in the CH4 evolution rate (15.524 μmol g–1 h–1) and 9.85-fold improvements in CO generation rate (53.869 μmol g–1 h–1). Density functional theory simulations further prove that the presence of B–H bonding in the composite is favorable for CO2 adhesion and activation in the reaction process. Thus, we believe that the implantation of functional active sites into the porous matrix provides important insights for preparation of a highly efficient photocatalyst.
Pub.: 29 May '18, Pinned: 30 Jun '18
Abstract: The preparation of cost-effective, stable catalysts for the selective reduction of carbon dioxide (CO2) to C1 products such as methanol is extremely important because methanol can be used directly as a fuel or it can be converted into other value-added products. However, the catalysts currently used for the reduction of CO2 to methanol exhibit poor selectivity, poor stability and very low faradaic efficiency. Herein, we used low-cost, stable cuprous oxide/polypyrrole (Cu2O/Ppy) particles having structures of octahedra and icosahedra (microflowers) that were prepared on linen texture (LT) papers for the selective reduction of CO2 to form a value-added single C1 product, methanol. The Cu2O/Ppy particles possessing both octahedral and microflower shapes with exposed low-index (111) facets and high-index (311) and (211) facets are denoted as Cu2O(OL-MH)/Ppy particles. The as-prepared Cu2O(OL-MH)/Ppy particles exhibited high catalytic activity and selectivity towards the electrochemical reduction of CO2 at -0.85 V vs. RHE to form methanol, with a faradaic efficiency of 93 ± 1.2% and an average methanol formation rate of 1.61 ± 0.02 μmol m-2 s-1. The X-ray photoelectron spectroscopy (XPS) analysis revealed that the pyrrolic nitrogen atoms present in the Ppy shell played a dominant role as active sites for CO2 molecules. The Raman bands of Ppy and Cu2O did not shift even after being subjected to electrolysis for several hours, suggesting superior stability of the Cu2O(OL-MH)/Ppy particles. The high resolution microscopic, spectroscopic, diffraction and electrochemical analysis results clearly revealed that the Ppy shell protected the Cu2O particles and avoided corrosion, dissolution, and structural and crystal facet changes, leading to greater stability. The low-cost, durable, flexible, and catalytically active Cu2O(OL-MH)/Ppy LT paper holds great potential for catalytic, photocatalytic and energy storage applications.
Pub.: 14 Jun '18, Pinned: 30 Jun '18