ORCID Profile
0000-0001-7089-7587
Current Organisation
University of East Anglia
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Publisher: Springer Science and Business Media LLC
Date: 07-01-2016
DOI: 10.1038/SREP17243
Abstract: New and novel 3D hierarchical porous graphene aerogels (HPGA) with uniform and tunable meso-pores (e.g., 21 and 53 nm) on graphene nanosheets (GNS) were prepared by a hydrothermal self-assembly process and an in-situ carbothermal reaction. The size and distribution of the meso-pores on the in idual GNS were uniform and could be tuned by controlling the sizes of the Co 3 O 4 NPs used in the hydrothermal reaction. This unique architecture of HPGA prevents the stacking of GNS and promises more electrochemically active sites that enhance the electrochemical storage level significantly. HPGA, as a lithium-ion battery anode, exhibited superior electrochemical performance, including a high reversible specific capacity of 1100 mAh/g at a current density of 0.1 A/g, outstanding cycling stability and excellent rate performance. Even at a large current density of 20 A/g, the reversible capacity was retained at 300 mAh/g, which is larger than that of most porous carbon-based anodes reported, suggesting it to be a promising candidate for energy storage. The proposed 3D HPGA is expected to provide an important platform that can promote the development of 3D topological porous systems in a range of energy storage and generation fields.
Publisher: Elsevier BV
Date: 04-2008
Publisher: Wiley
Date: 09-12-2022
Abstract: Platinum (Pt) remains the benchmark electrocatalyst for alkaline hydrogen evolution reaction (HER), but its industry‐scale hydrogen production is severely h ered by the lack of well‐designed durable Pt‐based materials that can operate at ere‐level current densities. Herein, based on the original oxide layer and parallel convex structure on the surface of nickel foam (NF), a 3D quasi‐parallel architecture consisting of dense Pt nanoparticles (NPs) immobilized oxygen vacancy‐rich NiO x heterojunctions (Pt/NiO x ‐O V ) as an alkaline HER catalyst is developed. A combined experimental and theoretical studies manifest that anchoring Pt NPs on NiO x ‐O V leads to electron‐rich Pt species with altered density of states (DOS) distribution, which can efficiently optimize the d‐band center and the adsorption of reaction intermediates as well as enhance the water dissociation ability. The as‐prepared catalyst exhibits extraordinary HER performance with a low overpotential of 19.4 mV at 10 mA cm −2 , a mass activity 16.3‐fold higher than that of 20% Pt/C, and a long durability of more than 100 h at 1000 mA cm −2 . Furthermore, the assembled alkaline electrolyzer combined with NiFe‐layered double hydroxide requires extremely low voltage of 1.776 V to attain 1000 mA cm −2 , and can operate stably for more than 400 h, which is rarely achieved.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TA10657H
Publisher: American Chemical Society (ACS)
Date: 15-10-2008
DOI: 10.1021/ES801087F
Abstract: The effects of passing ozone over different zeolite and MCM-41 materials to remove toluene were investigated. Different ozone-to-toluene ratios were used to evaluate the catalytic performance during ozonation. The micro- and meso-porous materials removed about 50% of the toluene via adsorption and another 20-40% was decomposed by ozonation, which was catalytically enhanced by the zeolite and MCM-41 materials. The catalytic reaction portion increased by using a higher ozone inlet concentration and it was further enhanced to around 50% with the use of more adsorbents or with longer residence times. Inside the porous structure of the material, ozone was either decomposed into active atomic oxygen for reactions or converted into oxygen for active site regeneration. The number of Lewis acid sites in the adsorbents for ozone decomposition and byproduct generation during the reactions limit the catalytic activities. Trace amounts of intermediates including aldehydes and organic acids were quantified in the ozonation process. A higher ozone inlet concentration helped to reduce intermediate species formation but it led to more residual ozone in the exhaust. The high adsorption capability of the zeolite and MCM-41 adsorbents could serve as reservoirs for suppressing the release of intermediate species to the exhaust.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TA05350G
Abstract: An organic redox flow electrode in FCDI is proposed to achieve quick salt removal and low energy consumption. The energy consumption is zero using a photoanode as the driving force.
Publisher: American Scientific Publishers
Date: 04-2012
Abstract: Crystalline Co3O4 nanowire arrays freely supported on Ni foam are successfully synthesized using a template-free method. The effects of reaction time, concentration of reactants, and temperature on the morphology of the nanowires are studied. The results indicate that uniform Co3O4 nanowires could be synthesized at 90 degrees C, and a transformation of the s les' morphology from nanoparticles to nanowires to microrods is observed by controlling the concentration of the reactants. The well-ordered nanowires synthesized under the selected reaction conditions are composed of spinel Co3O4 with diameters of 500-580 nm and lengths of 6-8 microm. These nanowires show good catalytic activity for the ozone catalytic oxidation of toluene.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM33085G
Publisher: Elsevier BV
Date: 03-2008
Publisher: Elsevier BV
Date: 07-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4TA03138E
Abstract: We reported a simple and green method to fabricate various palladium (0.8, 2.17, 7.65 wt%) loaded graphene aerogel deposited on nickel foam (Pd/GA/NF) as binder-free direct electrodes for electro-oxidation of methanol and ethanol.
Publisher: Springer Science and Business Media LLC
Date: 18-09-2015
DOI: 10.1038/SREP14229
Abstract: New and novel 3D hierarchical porous graphene aerogels (HPGA) with uniform and tunable meso-pores (e.g., 21 and 53 nm) on graphene nanosheets (GNS) were prepared by a hydrothermal self-assembly process and an in-situ carbothermal reaction. The size and distribution of the meso-pores on the in idual GNS were uniform and could be tuned by controlling the sizes of the Co 3 O 4 NPs used in the hydrothermal reaction. This unique architecture of HPGA prevents the stacking of GNS and promises more electrochemically active sites that enhance the electrochemical storage level significantly. HPGA, as a lithium-ion battery anode, exhibited superior electrochemical performance, including a high reversible specific capacity of 1100 mAh/g at a current density of 0.1 A/g, outstanding cycling stability and excellent rate performance. Even at a large current density of 20 A/g, the reversible capacity was retained at 300 mAh/g, which is larger than that of most porous carbon-based anodes reported, suggesting it to be a promising candidate for energy storage. The proposed 3D HPGA is expected to provide an important platform that can promote the development of 3D topological porous systems in a range of energy storage and generation fields.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0GC01191F
Abstract: A consumption-free electrochemical desalination method is demonstrated to work based on a light-driven photocathode with a Pt/CdS/CZTS/Mo architecture.
Publisher: Informa UK Limited
Date: 22-09-2010
Publisher: Wiley
Date: 11-2021
DOI: 10.1002/CEY2.155
Abstract: Aluminum–metal batteries show great potential as next‐generation energy storage due to their abundant resources and intrinsic safety. However, the crucial limitations of metallic Al anodes, such as dendrite and corrosion problems in conventional aluminum–metal batteries, remain challenging and elusive. Here, we report a novel electrodeposition strategy to prepare an optimized 3D Al anode on carbon cloth with an uniform deposition morphology, low local current density, and mitigatory volume change. The symmetrical cells with the 3D Al anode show superior stable cycling ( h) and low‐voltage hysteresis (~170 mV) at 0.5 mA cm −2 . High reversibility (~99.7%) is achieved for the Al plating/stripping. The graphite | | Al‐4/CC full batteries show a long lifespan of 800 cycles with 54 mAh g −1 capacity at a high current density of 1000 mA g −1 , benefiting from the high capacitive‐controlled distribution. This study proposes a novel strategy to design 3D Al anodes for metallic‐Al‐based batteries by eliminating the problems of planar Al anodes and realizing the potential applications of aluminum–graphite batteries.
Publisher: ASMEDC
Date: 2007
Abstract: This study investigated the performance of multi-transition metal (Cu, Cr, Ni and Co) ions exchanged zeolite 13X catalysts on methane emission abatement, especially at methane level of the exhaust from natural gas fueled vehicles. Catalytic activity of methane combustion using multi-ions exchanged catalyst was studied under different parameters: mole % of metal loading, inlet velocity and inlet methane concentration at atmospheric pressure and 500 °C. Performance of the catalysts was investigated and explained in terms of the apparent activation energy, number of active sites and BET surface area of the catalyst. This study showed that the multi-ions exchanged catalyst outperformed the single-ions exchanged and the acidified 13X catalysts. Lengthening the residence time could also lead to higher methane conversion %. Catalytic activity of the catalysts was influenced by the mole % of metal loading which played important roles in affecting the apparent activation energy of methane combustion, active sites and also the BET surface area of the catalyst. Increasing mole % of metal loading in the catalyst decreased the apparent activation energy for methane combustion and also the BET surface area of the catalyst. In view of these, there existed an optimized mole % of metal loading where the highest catalytic activity was observed.
Publisher: Elsevier BV
Date: 11-2013
Publisher: Wiley
Date: 15-09-2021
Abstract: As anodes for metal‐ion batteries, metal phosphides usually suffer from severe capacity degradation because of their huge volume expansion and unstable solid electrolyte interphase (SEI), especially for potassium‐ion batteries (PIBs). To address these issues, this study proposes amorphous phosphates acting as buffer materials. Ten types of metal phosphide composites embedded with in situ‐formed amorphous phosphates are prepared by one‐step ball milling using red phosphorus (RP) and the corresponding metal oxides (MOs) as starting materials. A zinc phosphide composite is selected for further study as a PIB anode. Benefitting from the effective suppression of volume variation, a KF‐rich SEI is formed on the electrode surface in the KFSI‐based electrolyte. The zinc phosphide composite exhibits a high reversible specific capacity and outstanding long‐term cycling stability (476 mAh g −1 over 350 cycles at 0.1 A g −1 after going through a rate capability test and 177 mAh g −1 after 6000 cycles at 1.0 A g −1 ) and thus achieves the best cycling performance among all reported metal phosphide‐based anodes for PIBs. This study highlights a low‐cost and effective strategy to guide the development of metal phosphides as high‐performance anodes for PIBs.
Publisher: ASMEDC
Date: 2009
DOI: 10.1115/ES2009-90128
Abstract: The potential use of biomass co-combustion derived fly-ash products and zeolite 13X for the elimination of volatile organic compounds (VOCs) using ozone was investigated for an integrated solar-assisted air purification and desiccant cooling system. Fly-ash products from rice husk-coal co-combustion at different biomass blending ratios were used as the adsorbent/catalyst materials. The material characteristics of the adsorbent/catalyst materials such as metal content and surface area were compared and correlated with the catalytic activities. It was found that the surface area and the metal constitutes have made the catalytic activities over the fly-ash products from biomass co-combustion superior to that from coal-only combustion. The elevated reaction temperatures from 25°C to 75°C also have significant effects on the removal of VOCs. The apparent activation energies of the reaction path over the fly-ash products with the addition of ozone to the air were reduced, when compared with the use of air as an oxidant. On the other hand, the potential synergy to Zeolite 13X was explored. The combined catalytic ozonation and adsorption enhanced the VOCs removal and at the same time reduced the intermediates emission. Furthermore, the hydrophilic properties of zeolite 13X could be utilized to handle the latent load of the solar-assisted ventilation system for energy conservations.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C002669G
Publisher: Elsevier BV
Date: 05-2007
DOI: 10.1016/J.JHAZMAT.2006.08.077
Abstract: This study investigated the performance of a combined ozone and zeolite system in eliminating gaseous toluene which is a major contaminant in many industrial and indoor environments. The hypothesis that the removal of toluene by ozone can be substantially affected by confining the oxidation reaction in a zeolite structure was evaluated. The degradation of toluene seemed to be contributed by the active oxygen atom generated from the decomposition of ozone at the Lewis acid sites in the zeolite 13X. Air containing toluene levels at 1.5, 2 and 3 ppm was injected with ozone in the range of 0-6 ppm before being vented into a fixed amount of 3600 g zeolite 13X with 90 mm bed-length. The experimental results showed that the elimination rate of toluene was significantly enhanced when compared to using zeolite or ozone alone. In particular, over 90% of the 1.5 ppm toluene was removed when 6 ppm ozone was used at 40% relative humidity level. Deactivation of the zeolite 13X after a few hours of reactions under the current experimental conditions was probably due to the adsorbed water, carbon dioxide and the reaction by-products. The residue species left in the zeolite and the intermediate species in the exhaust gas stream were characterized by FT-IR, GC-MS and HP-LC methods, respectively. A distinctive peak of O atom attached to the Lewis acid site at 1380 cm(-1) was found in the FT-IR spectrum and trace amount of aldehydes was found to be the reaction by-products.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Kwan San Hui.