Postsynthetic treatment of nickel–iron layered double hydroxides for the optimum catalysis of the oxygen evolution reaction

D.T., S.J., J.C., and V.N. wish to thank the support of the ERC CoG, 3D2DPring (GA 681544) and PoC Powering_eTextiles (GA 861673) and SFI AMBER (12/RC/2278_P2). The authors would like to thank the Advanced Microscopy Lab and CRANN Trinity College Dublin for providing STEM-EDX measurements. This publication has emanated from research supported in part by a grant from Science Foundation Ireland under Grant number 12/RC/2278_P2. For the purpose of Open Access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission. Publisher Copyright: © 2021, The Author(s).Nickel–iron-layered double hydroxide (NiFe LDH) platelets with high morphological regularity and submicrometre lateral dimensions were synthesized using a homogeneous precipitation technique for highly efficient catalysis of the oxygen evolution reaction (OER). Considering edge sites are the point of activity, efforts were made to control platelet size within the synthesized dispersions. The goal is to controllably isolate and characterize size-reduced NiFe LDH particles. Synthetic approaches for size control of NiFe LDH platelets have not been transferable based on published work with other LDH materials and for that reason, we instead use postsynthetic treatment techniques to improve edge-site density. In the end, size-reduced NiFe LDH/single-wall carbon nanotube (SWCNT) composites allowed to further reduce the OER overpotential to 237 ± 7 mV ( = 0.16 ± 0.01 μm, 20 wt% SWCNT), which is one of the best values reported to date. This approach as well improved the long-term activity of the catalyst in operating conditions.publishersversionpublishe

WANDA: A Radically New Approach for Low-Cost Environmental Monitoring

The cost of monitoring pollutants within natural waters is of major concern. Existing and forthcoming bodies of legislation continually drive the demand for spatial and selective monitoring of key pollutants within our environment. Although research and commercial entities continue to drive down the cost of the infrastructure involved in environmental sensing systems (with an aim to increase scalability), the realisation of deploying a number of such systems even now remains out of reach. High cost and maintenance continue to persist as the major limiting factors. The aim of this work is to combine recent advances in robotics with chemical sensing techniques to remove all but the chemo-responsive material from each sensing node, and package the sensing element within a low cost, mobile, biomimetic robotic fish for effective water quality monitoring. Consequently, this approach is believed to radically reduce the systemic cost and maintenance per node and in doing so it will increase the scalability for spatial and selective monitoring of key pollutants within our environment

Wireless aquatic navigator for detection and analysis (WANDA)

The cost of monitoring and detecting pollutants in natural waters is of major concern. Current and forthcoming bodies of legislation will continue to drive demand for spatial and selective monitoring of our environment, as the focus increasingly moves towards effective enforcement of legislation through detection of events, and unambiguous identification of perpetrators. However, these monitoring demands are not being met due to the infrastructure and maintenance costs of conventional sensing models. Advanced autonomous platforms capable of performing complex analytical measurements at remote locations still require individual power, wireless communication, processor and electronic transducer units, along with regular maintenance visits. Hence the cost base for these systems is prohibitively high, and the spatial density and frequency of measurements are insufficient to meet requirements. In this paper we present a more cost effective approach for water quality monitoring using a low cost mobile sensing/communications platform together with very low cost stand-alone ‘satellite’ indicator stations that have an integrated colorimetric sensing material. The mobile platform is equipped with a wireless video camera that is used to interrogate each station to harvest information about the water quality. In simulation experiments, the first cycle of measurements is carried out to identify a ‘normal’ condition followed by a second cycle during which the platform successfully detected and communicated the presence of a chemical contaminant that had been localised at one of the satellite stations

The benefit of the European User Community from transnational access to national radiation facilities

Transnational access (TNA) to national radiation sources is presently provided via programmes of the European Commission by BIOSTRUCT-X and CALIPSO with a major benefit for scientists from European countries. Entirely based on scientific merit, TNA allows all European scientists to realise synchrotron radiation experiments for addressing the Societal Challenges promoted in HORIZON2020. In addition, by TNA all European users directly take part in the development of the research infrastructure of facilities. The mutual interconnection of users and facilities is a strong prerequisite for future development of the research infrastructure of photon science. Taking into account the present programme structure of HORIZON2020, the European Synchrotron User Organization (ESUO) sees considerable dangers for the continuation of this successful collaboration in the future

X-ray spectroscopic study of the electronic structure of the high-dielectric-constant material CaCu3Ti4O12

The element-specific valence- and conduction-band densities of states for the high-dielectric-material CaCu 3 Ti 4 O 12 have been measured using soft x-ray emission and absorption spectroscopies. Ti L a , b ,Cu L a , b , and O K soft x-ray emission spectra of CaCu 3 Ti 4 O 12 were measured with monochromatic photon excitation on selected energies above the Ti and Cu L 2,3 and O K absorption edges, respectively. X-ray absorption spectra were recorded at the same edges. The electronic structure was also calculated using density functional theory employing the full-potential linearized augmented plane-wave method. Excellent agreement is seen between the results of these calculations and the measured x-ray emission and absorption spectra. This agreement is particularly good at the O K edge where the resonant behavior of the x-ray emission spectrum can be attributed directly to s - and p -state emission from valence-band O 2 p states when in resonance with p * and s * conduction-band O 2 p states. Resonant inelastic x-ray scattering is observed at the Ti L 2,3 absorption edge and is compared to previous studies of Ti containing perovskite compounds. The role of Cu 3 d states in determin- ing the band gap of this material is discusse

Resonant Soft X-Ray Inelastic Scattering and Soft X-Ray Emission Study of the Electronic Structure of alpha-MoO3

The electronic structure of quasi-low-dimensional solids is a topic of enduring interest due to the complex many-body interactions that exist in such materials and their resulting exotic physical properties. A well studied class of such materials is the quasi-low-dimensional metals known collectively as molybdenum oxide bronzes. These materials are all derived from the band insulator -MoO 3 . We report here a study of the electronic structure of -MoO 3 using resonant inelastic x-ray scattering and soft x-ray emission spectroscopy. We observe significant variation in x-ray scattering as a function of the relative orientation of the polarization vector of the incident light and the crystal axes. We interpret our data using a model of k -selective soft x-ray scatterin

Nitrogen-doped pyrolytic carbon films as highly electrochemically active electrodes.

Nitrogen-doped Pyrolytic Carbon (N-PyC) films were employed as an electrode material in electrochemical applications. PyC was grown by via non-catalysed chemical vapour deposition and subsequently functionalised via exposure to ammonia?hydrogen plasma. The electrochemical properties of the N-PyC films were investigated using the ferri/ferro-cyanide and hexaamine ruthenium( III ) chloride redox probes. Exceptional electron transfer properties were observed and quantified for the N-PyC compared to the as-grown films. X-ray photoelectron spectroscopy confirmed the presence of nitrogen in edge plane graphitic configurations and the surface of the N-PyC was investigated using scanning electron microscopy and atomic force microscopy. The excellent electrochemical performance of the N-PyC, in addition to its ease of preparation, renders this material ideal for applications in electrochemical sensin

Soft x-ray spectroscopic investigation of ferromagnetic Co-doped ZnO

The electronic properties of cobalt-doped ZnO were investigated through site-selective and element-sensitive x-ray-absorption spectroscopy in the vicinity of the Co L2,3 edge, the oxygen K edge, and at the Zn L3 edge. The spectroscopic measurements of the ferromagnetic cobalt-doped ZnO films appear to have additional components in the O K edge x-ray-absorption spectrum not observed in the undoped films. The observed features may derive from both hybridization with unoccupied Co 3d states and also from lattice defects such as oxygen vacancies. Only minor changes in the Zn L3 edge spectra were observed. These observations are consistent with a polaron percolation model in which the ferromagnetic coupling is mediated by shallow donor electrons trapped in oxygen vacancies and couples the Co atoms substituted on Zn sites in the hexagonal wurtzite ZnO structure

Soft x-ray spectroscopic investigation of ferromagnetic Co-doped ZnO

The electronic properties of cobalt-doped ZnO were investigated through site-selective and element-sensitive x-ray-absorption spectroscopy in the vicinity of the Co L2,3 edge, the oxygen K edge, and at the Zn L3 edge. The spectroscopic measurements of the ferromagnetic cobalt-doped ZnO films appear to have additional components in the O K edge x-ray-absorption spectrum not observed in the undoped films. The observed features may derive from both hybridization with unoccupied Co 3d states and also from lattice defects such as oxygen vacancies. Only minor changes in the Zn L3 edge spectra were observed. These observations are consistent with a polaron percolation model in which the ferromagnetic coupling is mediated by shallow donor electrons trapped in oxygen vacancies and couples the Co atoms substituted on Zn sites in the hexagonal wurtzite ZnO structure