Imperial College London

Professor Jason Riley

Faculty of EngineeringDepartment of Materials

Professor of Materials Electrochemistry
 
 
 
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Contact

 

+44 (0)20 7594 6751jason.riley

 
 
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Location

 

B3.37Bessemer BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

96 results found

Hadden JHL, Ryan MP, Riley DJ, 2019, Examining the charging behaviour of nickel hydroxide nanomaterials, Electrochemistry Communications, Vol: 101, Pages: 47-51, ISSN: 1388-2481

To investigate the depth of charging at the material surface, batches of nickel hydroxide nanoparticles were hydrothermally synthesised in the range 3–450 nm. Any surfactant added was removed post synthesis using ozone. The capacity per gram (Cs) increased and the capacity per unit area (CA) was constant with decreasing particle size down to 20 nm. Further reduction in particle size resulted in a decrease in both CS and CA, suggesting the Ni(OH)2 is charged to a depth in the order of 10 nm at the charging rate studied. The results obtained have implications in the design of Ni(OH)2 electrodes in charge storage applications.

Journal article

Jiang Q, Ji C, Riley DJ, Xie Fet al., 2019, Boosting the efficiency of photoelectrolysis by the addition of non-noble plasmonic metals: Al & Cu, Nanomaterials, Vol: 9, ISSN: 2079-4991

Solar water splitting by semiconductor based photoanodes and photocathodes is one of the most promising strategies to convert solar energy to chemical energy to meet the high demand for energy consumption in modern society. However, the state-of-the-art efficiency is too low to fulfill the demand. To overcome this challenge and thus enable the industrial realization of a solar water splitting device, different approaches have been taken to enhance the overall device efficiency, one of which is the incorporation of plasmonic nanostructures. Photoanodes and photocathodes coupled to the optimized plasmonic nanostructures, matching the absorption wavelength of the semiconductors, can exhibit a significantly increased efficiency. So far, gold and silver have been extensively explored to plasmonically enhance water splitting efficiency, with disadvantages of high cost and low enhancement. Instead, non-noble plasmonic metals such as aluminum and copper, are earth-abundant and low cost. In this article, we review their potentials in photoelectrolysis, towards scalable applications.

Journal article

Song W, Liu X, Wu B, Brandon N, Shearing PR, Brett DJL, Xie F, Jason Riley Det al., 2018, Sn@C evolution from yolk-shell to core-shell in carbon nanofibers with suppressed degradation of lithium storage, Energy Storage Materials, ISSN: 2405-8297

Metallic Sn has high conductivity and high theoretical capacity for lithium storage but it suffers from severe volume change in lithiation/delithiation leading to capacity fade. Yolk-shell and core-shell Sn@C spheres interconnected by carbon nanofibers were synthesized by thermal vapor and thermal melting of electrospun nanofibers to improve the cycling stability. Sn particles in yolk-shell spheres undergo dynamic structure evolution during thermal melting to form core-shell spheres. The core-shell spheres linked along the carbon nanofibers show outstanding performance and are better than the yolk-shell system for lithium storage, with a high capacity retention of 91.8% after 1000 cycles at 1 A g-1. The superior structure of core-shell spheres interconnected by carbon nanofibers has facile electron conductivity and short lithium ion diffusion pathways through the carbon nanofibers and shells, and re-develops Sn@C structures with Sn clusters embedded into carbon matrix during electrochemical cycling, enabling the high performance.

Journal article

Ballantyne AD, Hallett JP, Riley DJ, Shah N, Payne DJet al., 2018, Lead acid battery recycling for the twenty-first century, Royal Society Open Science, Pages: 171368-171368, ISSN: 2054-5703

There is a growing need to develop novel processes to recover lead from end-of-life lead-acid batteries, due to increasing energy costs of pyrometallurgical lead recovery, the resulting CO2 emissions and the catastrophic health implications of lead exposure from lead-to-air emissions. To address these issues, we are developing an iono-metallurgical process, aiming to displace the pyrometallurgical process that has dominated lead production for millennia. The proposed process involves the dissolution of Pb salts into the deep eutectic solvent (DES) Ethaline 200, a liquid formed when a 1 : 2 molar ratio of choline chloride and ethylene glycol are mixed together. Once dissolved, the Pb can be recovered through electrodeposition and the liquid can then be recycled for further Pb recycling. Firstly, DESs are being used to dissolve the lead compounds (PbCO3, PbO, PbO2 and PbSO4) involved and their solubilities measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The resulting Pb2+ species are then reduced and electrodeposited as elemental lead at the cathode of an electrochemical cell; cyclic voltammetry and chronoamperometry are being used to determine the electrodeposition behaviour and mechanism. The electrodeposited films were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). We discuss the implications and opportunities of such processes.

Journal article

Riley DJ, Song W, Xie F, Shearing PR, Brett D, Aguadero A, Kangyu Jet al., 2018, Co3O4 hollow nanospheres doped with ZnCo2O4 via thermal vapor mechanism for fast lithium storage., Energy Storage Materials, Vol: 14, Pages: 324-334, ISSN: 2405-8297

Binary metal oxides offer improved anode materials in lithium ion batteries owing to enhanced electrical conductivity but suffer from large volume expansion on lithiation. A novel route to hollow Co3O4 nanospheres doped with ZnCo2O4 is demonstrated that mitigates the expansion issue and shows excellent performance at high current densities. The synthetic route is based on the pyrolysis of binary metal-organic-frameworks (MOFs) with the controlled loss of zinc tuning the micro and nanostructure of the material through a thermal vapor mechanism. The optimal structures, that contain hollow Co3O4 spheres of ca. 50 nm diameter doped with ZnCo2O4, show a specific capacity of 890 mAh g−1 at a current rate of 0.1 A g−1 and show a similar specific capacity at 1 A g−1 after 120 cycles at high current densities. The kinetics of lithiation/delithiation changes from diffusion-controlled to a surface-controlled process by the nanosizing of the particles. The resultant faster ion diffusion and capacitive storage for lithium ions are responsible for the extraordinary high-rate performance of the hollow structures.

Journal article

Song W, Brugge R, Theodorou IG, Lim AL, Yang Y, Zhao T, Burgess CH, Johnson ID, Aguadero A, Shearing PR, Brett DJL, Xie F, Riley DJet al., 2017, Enhancing Distorted Metal Organic Framework Derived ZnO as Anode Material for Lithium Storage by the Addition of Ag2S Quantum Dots., ACS Applied Materials and Interfaces, Vol: 9, Pages: 37823-37831, ISSN: 1944-8244

The lithium storage properties of the distorted metal-organic framework (MOF) derived nanosized ZnO@C are significantly improved by the introduction of Ag2S quantum dots (QDs) during the processing of the material. In the thermal treatment, the Ag2S QDs react to produce Ag nanoparticles and ZnS. The metal nanoparticles act to shorten electron pathways and improve the connectivity of the matrix and the partial sulfidation of the ZnO surface improves the cycling stability of the material. The electrochemical properties of ZnO@C, Ag2S QDs treated ZnO@C and the amorphous carbon in ZnO@C have been compared. The small weight ratio of Ag2S QDs to ZnO@C at 1:180 shows the best performance in lithium storage. The exhibited specific capacities are improved and retained remarkably in the cycling at high current rates. At low current densi-ties (200 mA g-1) treatment of ZnO@C with Ag2S QDs results in a 38% increase in the specific capacity.

Journal article

Amdursky N, Wang X, Meredith P, Riley DJ, Payne DJ, Bradley D, Stevens MMet al., 2017, Electron Hopping Across Hemin-Doped Serum Albumin Mats on Centimetre-Length Scales, Advanced Materials, Vol: 29, ISSN: 1521-4095

Exploring long-range electron transport across protein assemblies is a central interest in both the fundamental research of biological processes and the emerging field of bioelectronics. This work examines the use of serum-albumin-based freestanding mats as macroscopic electron mediators in bioelectronic devices. In particular, this study focuses on how doping the protein mat with hemin improves charge-transport. It is demonstrated that doping can increase conductivity 40-fold via electron hopping between adjacent hemin molecules, resulting in the highest measured conductance for a protein-based material yet reported, and transport over centimeter length scales. The use of distance-dependent AC impedance and DC current–voltage measurements allows the contribution from electron hopping between adjacent hemin molecules to be isolated. Because the hemin-doped serum albumin mats have both biocompatibility and fabrication simplicity, they should be applicable to a range of bioelectronic devices of varying sizes, configurations, and applications.

Journal article

Riley DJ, Song W, Lischner, Rocha VG, Qin H, Qi J, Hadden JHL, Mattevi, Xie Fet al., 2017, Tuning the Double Layer of Graphene Oxide through Phosphorus Doping for Enhanced Supercapacitance, ACS Energy Letters, Vol: 2, Pages: 1144-1149, ISSN: 2380-8195

The electrochemical double layer plays a fundamental role in energy storage applications. Control of the distribution of ions in the double layer at the atomistic scale offers routes to enhanced material functionality and device performance. Here we demonstrate how the addition of an element from the third row of the periodic table, phosphorus, to graphene oxide increases the measured capacitance and present density functional theory calculations that relate the enhanced charge storage to structural changes of the electrochemical double layer. Our results point to how rational design of materials at the atomistic scale can lead to improvements in their performance for energy storage.

Journal article

Song W, Chen J, Xiaobo J, Zhang X, Xie FE, Riley DJet al., 2016, Dandelion-shape TiO2/Multi-layer Graphene Composed of TiO2(B) Fibrils and Anatase TiO2 Pappi Utilizing Triphase Boundaries for Lithium Storage, Journal of Materials Chemistry A, Vol: 4, Pages: 8762-8768, ISSN: 2050-7496

Three‐dimensional dandelion‐shape TiO2/Multi‐layer graphene compound (TiO2/MLG) composed of TiO2(B) fibrils andanatase pappi structures has been synthesized as potential anode material for Li storage. Electronmicroscopy indicatesthat the composite contains triphase boundaries between anatase, TiO2(B) and graphene, which are responsible for theenhancement of energy storage and the decrease of electrode polarization. Cyclic voltammetric investigations indicatethat both Li+ insertion and pseudocapacitance contribute to charge storage. Ultrahigh specific capacities of 243 and 182mAh g‐1 have been obtained at 0.1 and 1 A g‐1, respectively. Moreover, the excellent capacity retention can reach 99.6%after 100 cycles with almost 100% coulombic efficiency at 0.1 A g‐1. The importance of the triphase boundary in enhancingthe storage of charge and transport of Li+ is demonstrated.

Journal article

Zhang X, Wu X, Centeno A, Ryan M, alford N, riley D, Xie Fet al., 2016, Significant broadband photocurrent enhancement by Au-CZTS core-shell nanostructured photocathodes, Scientific Reports, Vol: 6, ISSN: 2045-2322

Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap.

Journal article

Poll CG, Nelson G, Pickup DM, Chadwick AV, Riley D, Payne DJet al., 2016, Electrochemical Recycling of Lead from Hybrid Organic–Inorganic Perovskites using Deep Eutectic Solvents, Green Chemistry, Vol: 18, Pages: 2946-2955, ISSN: 1744-1560

The emerging field of lead-based hybrid organic-inorganic perovskite (HOIP) photovoltaic devices hasattracted a great deal of attention due to their very high conversion efficiencies and straightforwardfabrication methods. Unfortunately, a major obstacle to commercialization remains the high toxicity oflead. Whilst to date the focus has been on understanding and improving device performance, there hasbeen no reported effort to develop methods to recover and recycle the lead from these materials. In thiswork we demonstrate a simple, low-cost and environmentally friendly method of recycling lead fromHOIP photovoltaics by dissolution and selective electrodeposition using a deep eutectic solvent. Wedemonstrate that up to 99.8% of the lead is removed from the solvent. The results presented hereprovide a viable solution to lead-based HOIP photovoltaic recycling, and also open the possibility forproviding an alternative method to conventional smelting in the recovery and recycling of differentlead-based energy materials.

Journal article

Wu X, Zhang X, Price D, Ryan M, Riley J, Alford N, Centeno A, Xie Fet al., 2015, Broadband plasmon photocurrent generation from Au nanoparticles/ mesoporous TiO2 nanotube electrodes, Solar Energy Materials and Solar Cells, Vol: 138, Pages: 80-85, ISSN: 0927-0248

There has been an increasing interest in plasmon-induced enhancement of solar cells and more recently in the direct generation of photocurrent using noble metal nanoparticles with their Localised Surface Plasmon Resonance (LSPR) in the visual part of the spectrum. In this paper we report broadband plasmon photocurrent generation using novel Au nanoparticle incorporated mesoporous TiO2 nanotube electrodes. Plasmonic induced photocurrent due to hot electrons is observed over a broad wavelength range (~500 to 1000 nm). Incident photon-to-electron conversion efficiency (IPCE) measurements undertaken showed a maximum photocurrent enhancement of 200 fold around 700–730 nm wavelength.

Journal article

Teo GY, Ryan MP, Riley DJ, 2014, A mechanistic study on templated electrodeposition of one-dimensional TiO2 nanorods and nanotubes using TiOSO4 as a precursor, ELECTROCHEMISTRY COMMUNICATIONS, Vol: 47, Pages: 13-16, ISSN: 1388-2481

Journal article

King LA, Zhao W, Danos L, Riley DJet al., 2014, Activation of CdSe Quantum Dots after Exposure to Polysulfide, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 118, Pages: 14555-14561, ISSN: 1932-7447

Journal article

Yaacob KA, Riley DJ, 2014, Anodic Electrophoretic Deposition of TiO2 Nanoparticles Synthesized Using Sol Gel Method, International Conference on Nanoscience and Nanotechnology (NANO-SciTech 2013), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 633-+, ISSN: 1022-6680

Conference paper

Yaacob KA, Riley DJ, 2013, Formation of MUA (mercaptoundeconic acid)-capped CDSe nanoparticle films by electrophoretic deposition, CERAMICS INTERNATIONAL, Vol: 39, Pages: 8797-8803, ISSN: 0272-8842

Journal article

Zuehlsdorff TJ, Hine NDM, Spencer JS, Harrison NM, Riley DJ, Haynes PDet al., 2013, Linear-scaling time-dependent density-functional theory in the linear response formalism, JOURNAL OF CHEMICAL PHYSICS, Vol: 139, ISSN: 0021-9606

Journal article

King LA, Zhao W, Chhowalla M, Riley DJ, Eda Get al., 2013, Photoelectrochemical properties of chemically exfoliated MoS2, Journal of Materials Chemistry A

Chemically exfoliated monolayers of molybdenum disulfide (MoS2) are shown to be photoelectrochemically active and stable, highlighting the unexplored potential of 2D-crystals in photoelectrochemistry.

Journal article

Xie F, Pang J, Centeno A, Ryan M, Riley J, Alford Net al., 2013, Nanoscale control of Ag nanostructures for plasmonic fluorescence enhancement of near-infrared dyes, Nano Research, Vol: 6, Pages: 495-510, ISSN: 1998-0124

Potential utilization of proteins for early detection and diagnosis of various diseases has drawn considerable interest in the development of protein-based detection techniques. Metal induced fluorescence enhancement offers the possibility of increasing the sensitivity of protein detection in clinical applications. We report the use of tunable plasmonic silver nanostructures for the fluorescence enhancement of a near-infrared (NIR) dye (Alexa Fluor 790). Extensive fluorescence enhancement of ∼2 orders of magnitude is obtained by the nanoscale control of the Ag nanostructure dimensions and interparticle distance. These Ag nanostructures also enhanced fluorescence from a dye with very high quantum yield (7.8 fold for Alexa Fluor 488, quantum efficiency (Qy) = 0.92). A combination of greatly enhanced excitation and an increased radiative decay rate, leading to an associated enhancement of the quantum efficiency leads to the large enhancement. These results show the potential of Ag nanostructures as metal induced fluorescence enhancement (MIFE) substrates for dyes in the NIR “biological window” as well as the visible region. Ag nanostructured arrays fabricated by colloidal lithography thus show great potential for NIR dye-based biosensing applications.

Journal article

Xu N, Riley DJ, 2013, Nonlinear analysis of a classical system: The Faradaic process, ELECTROCHIMICA ACTA, Vol: 94, Pages: 206-213, ISSN: 0013-4686

Journal article

Xie F, Centeno A, Zou B, Ryan MP, Riley DJ, Alford NMet al., 2013, Tunable synthesis of ordered Zinc Oxide nanoflower-like arrays, JOURNAL OF COLLOID AND INTERFACE SCIENCE, Vol: 395, Pages: 85-90, ISSN: 0021-9797

Journal article

Orsi A, Riley DJ, 2013, Influence of Stress on Aluminum Anodization and Pore Ordering, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 160, Pages: D10-D12, ISSN: 0013-4651

Journal article

Xie F, Centeno A, Ryan MR, Riley DJ, Alford NMet al., 2013, Au nanostructures by colloidal lithography: from quenching to extensive fluorescence enhancement, J. Mater. Chem. B, Vol: 1, Pages: 536-543

Enhanced local electric fields are created by nanoparticles when pumped at wavelengths corresponding to Localised Surface Plasmon Resonance (LSPR) modes, leading to Metal Induced Fluorescence Enhancement (MIFE). This paper describes the fluorescent enhancement due to reproducible and tuneable Au nanostructures on glass substrates fabricated over large areas by colloidal lithography. Interparticle separation, particle resonance, and the fluorescent dye properties (quantum yield and emission/excitation wavelengths) are all important factors influencing the fluorescent enhancement. A maximum fluorescence enhancement of 69 times from near infra-red (NIR) dye Alexa Fluor[registered sign] 790 was observed.

Journal article

Wagstaffe SJ, Hill KE, Williams DW, Randle BJ, Thomas DW, Stephens P, Riley DJet al., 2012, Bispecific Antibody-Mediated Detection of the Staphylococcus aureus Thermonuclease, ANALYTICAL CHEMISTRY, Vol: 84, Pages: 5876-5884, ISSN: 0003-2700

Journal article

Cook JP, Riley DJ, 2012, Electrical switching of microgel swelling and collapse for display applications, JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, Vol: 50, Pages: 516-522, ISSN: 0887-6266

Journal article

Cook JP, Riley DJ, 2012, pH induced swelling of PVP microgel particles - A first order phase transition?, JOURNAL OF COLLOID AND INTERFACE SCIENCE, Vol: 370, Pages: 67-72, ISSN: 0021-9797

Journal article

King LA, Riley DJ, 2012, Importance of QD Purification Procedure on Surface Adsorbance of QDs and Performance of QD Sensitized Photoanodes, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 116, Pages: 3349-3355, ISSN: 1932-7447

Journal article

Tan KS, Riley J, 2012, Synthesis of Various Shapes of Titanate Nanoparticles via Hydrothermal Reaction, International Conference on Nanotechnology - Research and Commercialization (ICONT), Publisher: AMER INST PHYSICS, Pages: 97-114, ISSN: 0094-243X

Conference paper

Xu N, Riley J, 2011, Nonlinear analysis of a classical system: The double-layer capacitor, ELECTROCHEMISTRY COMMUNICATIONS, Vol: 13, Pages: 1077-1081, ISSN: 1388-2481

Journal article

Illy BN, Cruickshank AC, Da Campo R, Schumann S, Jones TS, Heutz SEM, McLachlan MA, McComb DW, Riley DJ, Ryan MPet al., 2011, Electrodeposition of ultrathin ZnO buffer layers with controllable orientation for photovoltaic applications, ISSN: 0065-7727

ZnO is one of the most promising materials for applications in nanotechnology due to its large band gap and high electron mobility. A large amount of work has focused on the study of nanostructured ZnO. However, two dimensional transparent compact layers are also of great interest as transparent conductive oxides in optoelectronic devices. Compact ZnO layers are usually deposited by methods which are generally costly thus significantly limiting their potential application. Electrodeposition is a low cost alternative, offering a high degree of control on the characteristics. In this work the effects of the deposition parameters on the film characteristics have been studied in order to fabricate the thinnest electrodeposited films ever reported and to tune the crystallographic orientation. Incorporation of the layer into an organic ZnO/P3HT:PCBM solar cell is used to demonstrate how a careful control of the orientation can dramatically improve the photovoltaic device efficiency.

Conference paper

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