The development of cost‐effective catalysts that can be fabricated at scale for electrochemical w... more The development of cost‐effective catalysts that can be fabricated at scale for electrochemical water oxidation is an ongoing challenge. Here it is shown that stainless‐steel AISI316 is an appropriate support electrode for a co‐electrodeposited Ni‐CeOx catalyst for the oxygen evolution reaction (OER) under alkaline conditions. Optimal OER performance is achieved via a cyclic voltammetric deposition protocol rather than constant potential deposition for the catalyst layer. An overpotential of 300 mV at a current density of 10 mA cm−2 is recorded with a Tafel slope of 43 mV dec−1 while the catalyst also demonstrates long‐term stability. It is also found that the catalyst layer changes significantly after the OER. This includes changes to the catalyst morphology, distribution of oxidation state, and speciation as well as the transformation from an entirely amorphous material into one containing crystalline regions. This simple one‐step electrodeposition process on a cost‐effective substrate should, in principle, facilitate the fabrication of low‐cost electrolyzers.
A sensitive and recyclable plasmonic nickel foam sensor has been developed for surface-enhanced R... more A sensitive and recyclable plasmonic nickel foam sensor has been developed for surface-enhanced Raman spectroscopy (SERS). A simple electrochemical method was used to deposit flower-shaped gold nanostructures onto nickel foam substrate. The high packing of the gold nanoflowers onto the nickel foam led to a high enhancement factor (EF) of 1.6 × 1011. The new SERS sensor was utilized for the direct determination of the broad-spectrum β-lactam carbapenem antibiotic meropenem in human blood plasma down to one pM. The sensor was also used in High Performance Liquid Chromatography (HPLC)-SERS assembly to provide fingerprint identification of meropenem in human blood plasma. Moreover, the SERS measurements were reproducible in aqueous solution and human blood plasma (RSD = 5.5%) and (RSD = 2.86%), respectively at 200 µg/mL (n = 3), and successfully recycled using a simple method, and hence, used for the repeated determination of the drug by SERS. Therefore, the new sensor has a strong pote...
Journal of Radioanalytical and Nuclear Chemistry, 2012
Page 1. Multi-element analysis of Ghanaian crude oils by instrumental neutron activation analysis... more Page 1. Multi-element analysis of Ghanaian crude oils by instrumental neutron activation analysis MK Appenteng • AA Golow • D. Carboo • D. Adomako • MS Hayford • AKK Yamoah • D. Saka • DK Sarfo Received: 1 December 2011 Ó Akadémiai Kiadó, Budapest, Hungary 2012 ...
A B ST R A C T The major (K, Mg, Cl, Ca and Na) and minor (Mn, Fe, Cr, Co, Cu and Br) elemental c... more A B ST R A C T The major (K, Mg, Cl, Ca and Na) and minor (Mn, Fe, Cr, Co, Cu and Br) elemental concentrations in different parts of Graviola ( Annona Muricata ) fruit including the fruit fibres, fruit cover, seed, fruit juice and seed cover were determined using instrumental neutron activation analysis. Their concentrations were found to vary in the various fruit parts. The elements Br, Ca, Cl, K, Mg, Mn and Na were recorded in all the various fruit parts. The highest concentrations recorded were K in the fruit cover (1.43±0.03%), fruit fibre (1.46±0.09%), fruit juice (2.28±0.15%) and seed (0.55±0.06%). In the seed cover however, Ca recorded the highest concentration of 0.25±0.02%. Chromium was below the detection limits of INAA in the fruit cover, fruit fibre and fruit juice. Copper and Fe were below detection limits in the fruit juice and seed cover respectively. The presence of Ca, Mg, Na, K, Co, Cr, Cu, Fe, Br, Cl and Mn reflects the function of the Graviola fruit as a source of essential nutrient elements. Therefore, the Graviola fruit becomes important in view of the fact that their regular consumption might help the body to attain the required levels of these essential nutrient elements.
Journal of Radioanalytical and Nuclear Chemistry, 2012
ABSTRACT This research work aimed at studying the metal content of water and tilapia fish sample,... more ABSTRACT This research work aimed at studying the metal content of water and tilapia fish sample, Oreochromis spp., from a wastewater-fed pond around the University of Cape Coast community using instrumental neutron activation analysis. The metals studied were Al, As, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, V and Zn. In the water samples the order of elemental concentrations at sampling point 1, in μg/g, was K (75.96 ± 0.92), Na (18.52 ± 0.35), Al (6.00 ± 0.89), Mn (3.28 ± 0.44), As (3.08 ± 0.40), Mg (1.56 ± 0.17), Ca (0.70 ± 0.08), Cu (0.54 ± 0.08) and V (0.04 ± 0.01). Co, Cr, Fe and Zn were below detection limits of INAA. The order of elemental concentrations in the water at point 2 was as follows: Na (4.99 ± 0.14), K (4.82 ± 0.89), Mn (4.40 ± 0.53), Mg (2.92 ± 0.37), Al (1.98 ± 0.21), As (0.69 ± 0.10), Ca (0.24 ± 0.07) and V (0.23 ± 0.06) with Co, Cr, Cu, Fe and Zn falling below the detection limit of INAA. The concentrations recorded for Al, As, Cu and Mn in the water samples were all above WHO permissible limits. The mean levels of heavy metals in the soft tissue of tilapia was of the order: K > Mg > Fe > Ca > Na > Al > Mn > Zn > V > Cu > Cr > Co. Arsenic was below detection limit. The transfer factor values calculated for the metals Al, Ca, K, Mg, Mn, Na and V were all greater than one indicating movement of metals from the water column to the tilapia species. The hazard index (HI) calculated for Al, Fe, Mn and V suggested possible occurrence of adverse health effects (HI > 1) where as the HI value obtained for Cr, Cu and Zn (i.e., HI < 1) suggested unlikely adverse effects occurring.
The development of cost‐effective catalysts that can be fabricated at scale for electrochemical w... more The development of cost‐effective catalysts that can be fabricated at scale for electrochemical water oxidation is an ongoing challenge. Here it is shown that stainless‐steel AISI316 is an appropriate support electrode for a co‐electrodeposited Ni‐CeOx catalyst for the oxygen evolution reaction (OER) under alkaline conditions. Optimal OER performance is achieved via a cyclic voltammetric deposition protocol rather than constant potential deposition for the catalyst layer. An overpotential of 300 mV at a current density of 10 mA cm−2 is recorded with a Tafel slope of 43 mV dec−1 while the catalyst also demonstrates long‐term stability. It is also found that the catalyst layer changes significantly after the OER. This includes changes to the catalyst morphology, distribution of oxidation state, and speciation as well as the transformation from an entirely amorphous material into one containing crystalline regions. This simple one‐step electrodeposition process on a cost‐effective substrate should, in principle, facilitate the fabrication of low‐cost electrolyzers.
A sensitive and recyclable plasmonic nickel foam sensor has been developed for surface-enhanced R... more A sensitive and recyclable plasmonic nickel foam sensor has been developed for surface-enhanced Raman spectroscopy (SERS). A simple electrochemical method was used to deposit flower-shaped gold nanostructures onto nickel foam substrate. The high packing of the gold nanoflowers onto the nickel foam led to a high enhancement factor (EF) of 1.6 × 1011. The new SERS sensor was utilized for the direct determination of the broad-spectrum β-lactam carbapenem antibiotic meropenem in human blood plasma down to one pM. The sensor was also used in High Performance Liquid Chromatography (HPLC)-SERS assembly to provide fingerprint identification of meropenem in human blood plasma. Moreover, the SERS measurements were reproducible in aqueous solution and human blood plasma (RSD = 5.5%) and (RSD = 2.86%), respectively at 200 µg/mL (n = 3), and successfully recycled using a simple method, and hence, used for the repeated determination of the drug by SERS. Therefore, the new sensor has a strong pote...
Journal of Radioanalytical and Nuclear Chemistry, 2012
Page 1. Multi-element analysis of Ghanaian crude oils by instrumental neutron activation analysis... more Page 1. Multi-element analysis of Ghanaian crude oils by instrumental neutron activation analysis MK Appenteng • AA Golow • D. Carboo • D. Adomako • MS Hayford • AKK Yamoah • D. Saka • DK Sarfo Received: 1 December 2011 Ó Akadémiai Kiadó, Budapest, Hungary 2012 ...
A B ST R A C T The major (K, Mg, Cl, Ca and Na) and minor (Mn, Fe, Cr, Co, Cu and Br) elemental c... more A B ST R A C T The major (K, Mg, Cl, Ca and Na) and minor (Mn, Fe, Cr, Co, Cu and Br) elemental concentrations in different parts of Graviola ( Annona Muricata ) fruit including the fruit fibres, fruit cover, seed, fruit juice and seed cover were determined using instrumental neutron activation analysis. Their concentrations were found to vary in the various fruit parts. The elements Br, Ca, Cl, K, Mg, Mn and Na were recorded in all the various fruit parts. The highest concentrations recorded were K in the fruit cover (1.43±0.03%), fruit fibre (1.46±0.09%), fruit juice (2.28±0.15%) and seed (0.55±0.06%). In the seed cover however, Ca recorded the highest concentration of 0.25±0.02%. Chromium was below the detection limits of INAA in the fruit cover, fruit fibre and fruit juice. Copper and Fe were below detection limits in the fruit juice and seed cover respectively. The presence of Ca, Mg, Na, K, Co, Cr, Cu, Fe, Br, Cl and Mn reflects the function of the Graviola fruit as a source of essential nutrient elements. Therefore, the Graviola fruit becomes important in view of the fact that their regular consumption might help the body to attain the required levels of these essential nutrient elements.
Journal of Radioanalytical and Nuclear Chemistry, 2012
ABSTRACT This research work aimed at studying the metal content of water and tilapia fish sample,... more ABSTRACT This research work aimed at studying the metal content of water and tilapia fish sample, Oreochromis spp., from a wastewater-fed pond around the University of Cape Coast community using instrumental neutron activation analysis. The metals studied were Al, As, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, V and Zn. In the water samples the order of elemental concentrations at sampling point 1, in μg/g, was K (75.96 ± 0.92), Na (18.52 ± 0.35), Al (6.00 ± 0.89), Mn (3.28 ± 0.44), As (3.08 ± 0.40), Mg (1.56 ± 0.17), Ca (0.70 ± 0.08), Cu (0.54 ± 0.08) and V (0.04 ± 0.01). Co, Cr, Fe and Zn were below detection limits of INAA. The order of elemental concentrations in the water at point 2 was as follows: Na (4.99 ± 0.14), K (4.82 ± 0.89), Mn (4.40 ± 0.53), Mg (2.92 ± 0.37), Al (1.98 ± 0.21), As (0.69 ± 0.10), Ca (0.24 ± 0.07) and V (0.23 ± 0.06) with Co, Cr, Cu, Fe and Zn falling below the detection limit of INAA. The concentrations recorded for Al, As, Cu and Mn in the water samples were all above WHO permissible limits. The mean levels of heavy metals in the soft tissue of tilapia was of the order: K > Mg > Fe > Ca > Na > Al > Mn > Zn > V > Cu > Cr > Co. Arsenic was below detection limit. The transfer factor values calculated for the metals Al, Ca, K, Mg, Mn, Na and V were all greater than one indicating movement of metals from the water column to the tilapia species. The hazard index (HI) calculated for Al, Fe, Mn and V suggested possible occurrence of adverse health effects (HI > 1) where as the HI value obtained for Cr, Cu and Zn (i.e., HI < 1) suggested unlikely adverse effects occurring.
Uploads
Papers by Daniel Sarfo