ORCID Profile
0000-0003-1097-9286
Current Organisation
University of Canterbury College of Engineering
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Publisher: MDPI AG
Date: 28-04-2023
DOI: 10.3390/INORGANICS11050191
Abstract: The structural determination of ultrasmall clusters remains a challenge due to difficulties in crystallisation. Often the atomically precise clusters undergo structural change under the influence of the environment. X-ray absorption spectroscopy (XAS) can be an attractive tool to study the electronic and geometric properties of such clusters deposited onto various supports under in situ conditions. Herein, [Au6(dppp)4](NO3)2, [Au9(PPh3)8](NO3)3, [Au13(dppe)5Cl2]Cl3, and Au101(PPPh3)21Cl5 clusters were studied using XAS. The clusters exhibited distinct features compared to bulk gold. XANES results show a systematic increase in the absorption edge energy and white line intensity, with a decrease in cluster nuclearity. The EXAFS of clusters are sensitive to nuclearity and ligands and were fitted with their known crystal structures. This study advances the understanding of the phosphine-ligated metal clusters relevant to practical applications in catalysis and sensing.
Publisher: American Chemical Society (ACS)
Date: 22-12-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0NA00927J
Abstract: A method is presented for the deposition of gold clusters onto reduced graphene oxide, without aggregation of the gold clusters.
Publisher: Wiley
Date: 07-06-2022
Abstract: The development of a stable and efficient Oxygen Reduction Reaction (ORR) electrocatalysts with high methanol tolerance is crucial for Direct Methanol Fuel Cells (DMFCs). Herein, triphenylphosphine (PPh 3 )‐ligated gold nanoclusters and complexes (AuNCs), Au 101 (PPh 3 ) 21 Cl 5 , Au 9 (PPh 3 ) 8 (NO 3 ) 3 , and Au 1 (PPh 3 )Cl supported on reduced graphene oxide (rGO) have been explored as methanol tolerant ORR electrocatalysts. Electrocatalytic performance of each AuNCs‐rGO was determined through linear sweep voltammograms (LSV) and cyclic voltammetry (CV) and compared with Pt/C. Size‐dependent ORR activity was observed which followed the size trend of Au 101 NC‐rGO Au 9 NC‐rGO Au 1 NC‐rGO. Repeated LSV and chrono erometry measurements revealed that the long‐term stability over 24 hours followed the trend Au 101 NC‐rGO Au 9 NC‐rGO∼Au 1 NC‐rGO and all were more stable than Pt/C. The methanol tolerance of each AuNCs‐rGO was also evaluated via LSV and CV. Size‐independent methanol tolerance with no noticeable change in ORR performance of AuNCs‐rGO was observed in the presence of methanol. AuNCs‐rGO nanocomposites are promising cathode electrocatalysts for DMFCs.
Publisher: MDPI AG
Date: 17-10-2022
DOI: 10.3390/NANO12203638
Abstract: Herein, the UV light photocatalytic activity of an Au101NC-AlSrTiO3-rGO nanocomposite comprising 1 wt% rGO, 0.05 wt% Au101(PPh3)21Cl5 (Au101NC), and AlSrTiO3 evaluated for H2 production. The synthesis of Au101NC-AlSrTiO3-rGO nanocomposite followed two distinct routes: (1) Au101NC was first mixed with AlSrTiO3 followed by the addition of rGO (Au101NC-AlSrTiO3:rGO) and (2) Au101NC was first mixed with rGO followed by the addition of AlSrTiO3 (Au101NC-rGO:AlSrTiO3). Both prepared s les were annealed in air at 210 °C for 15 min. Inductively coupled plasma mass spectrometry and high-resolution scanning transmission electron microscopy showed that the Au101NC adhered almost exclusively to the rGO in the nanocomposite and maintained a size less than 2 nm. Under UV light irradiation, the Au101NC-AlSrTiO3:rGO nanocomposite produced H2 at a rate 12 times greater than Au101NC-AlSrTiO3 and 64 times greater than AlSrTiO3. The enhanced photocatalytic activity is attributed to the small particle size and high loading of Au101NC, which is achieved by non-covalent binding to rGO. These results show that significant improvements can be made to AlSrTiO3-based photocatalysts that use cluster co-catalysts by the addition of rGO as an electron mediator to achieve high cluster loading and limited agglomeration of the clusters.
Publisher: Elsevier BV
Date: 2023
Location: New Zealand
No related grants have been discovered for Shailendra Kumar Sharma.