Boosting the electrochemical oxygen reduction activity of hemoglobin on fructose@graphene-oxide nanoplatforms

A metal-free oxygen reduction reaction (ORR) electrocatalyst with outstanding performance was obtained through an easy and one-pot synthesis of hemoglobin functionalized fructose@graphene-oxide (GO) nanocomposites. The active pyridinic nitrogen sites of the highly unfolded proteins together with the excellent electronic properties of GO appears to be the main factors causing the improved electrocatalytic activity

Tailoring the ORR and HER electrocatalytic performances of gold nanoparticles through metal–ligand interfaces

The oxygen reduction (ORR) and hydrogen evolution (HER) reactions are the most important cathodic processes involved in fuel cell and water splitting technologies, respectively. The development of bifunctional electrocatalyst materials plays a key role in the rapid advancement of these hydrogen-based renewable energy strategies. This work proposes citrate-stabilized gold nanoparticles (AuNPs) as a bifunctional electrocatalyst for ORR and HER. The capping ligand has a great influence on their resulting electrocatalytic performance. A simple ligand exchange method based on concentration gradients has been optimized. The surface structure of the different ligand-stabilized AuNPs was inferred by lead underpotential deposition (Pb-UPD). Static and dynamic electrochemical studies for both ORR and HER have been performed using different ligand-stabilized AuNPs as electrocatalysts, demonstrating that the citrate ligand confers the best performance. This work suggests that non-doped chemically synthesized AuNPs may be suitable as a bifunctional electrocatalyst in fuel cells and hydrogen production

Improving the electrocatalytic performance of sustainable Co/Carbon materials for oxygen evolution reaction by ultrasound and microwave assisted synthesis

The design of sustainable procedures for the preparation of cobalt/carbon-based materials as an anode for hydrogen fuel production through electrocatalytic water splitting has attracted much interest in the last few years. Herein, a novel environmentally friendly approach for the development of stable and active catalysts for the oxygen evolution reaction (OER) is reported. In detail, the methodology aimed at developing a sequence of composites having a low cobalt loading ( MW/US > MW > conventional heating, with the best sample requiring an overpotential of 365 mV to deliver a current density of 10 mA cm_2 and a Tafel slope of 58 mV dec_1

Application of a nickel hydroxide gold nanoparticles screen-printed electrode for impedimetric sensing of glucose in artificial saliva

In this study, a non-enzymatic glucose sensor (NEGs) based on the electrochemical deposition of nickel nanoparticles on screen-printed electrodes modified with gold nanoparticles, Ni(OH) 2 /AuNp/SPE, is obtained. SEM and XPS measurements, and electrochemical performance reveal synergist effects of gold nanoparticles in the behavior of the catalyst when both Ni(OH) 2 /SPE and Ni(OH) 2 /AuNp/SPE systems were compared. SEM images show a homogeneous distribution of nickel spherical nanoparticles (~85 nm of diameter) in Ni(OH) 2 /AuNp/SPE. XPS spectra indicate the presence of nickel(II), probably as nickel hydroxide catalyst at the surface. The electrochemical response of Ni(OH) 2 /AuNp/SPE toward glucose oxidation and the selectivity of the proposed NEG in the presence of ascorbic acid and dopamine were evaluated by Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). In the single-frequency impedance measurements, the imaginary impedance values (Z Im ) showed the best linear response with glucose concentration in the range of 0.10 to 2 mM, at 0.1 Hz and + 0.400 V vs Ag/AgCl. The calibration curve for 1/Z Im as a function of glucose concentration in artificial saliva samples was obtained with a slope of 0.073 KΩ −1 mM −1 , R 2 = 0.995, and limit of detection of 0.04 mM of glucose. Finally, impedimetric Ni(OH) 2 /AuNp/SPE was proposed for the quantification of glucose in non-blood samples.Fil: Rinaldi, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Rodríguez Castellón, Enrique. Universidad de Málaga; EspañaFil: Sobral, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Carballo, Romina Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentin

Boosting the electrochemical oxygen reduction activity of hemoglobin on fructose@graphene-oxide nanoplatforms

A metal-free oxygen reduction reaction (ORR) electrocatalyst with outstanding performance was obtained through an easy and one-pot synthesis of hemoglobin functionalized fructose@graphene-oxide (GO) nanocomposites. The active pyridinic nitrogen sites of the highly unfolded proteins together with the excellent electronic properties of GO appears to be the main factors causing the improved electrocatalytic activity. © The Royal Society of Chemistry

Tailoring the ORR and HER electrocatalytic performances of gold nanoparticles through metal-ligand interfaces

The oxygen reduction (ORR) and hydrogen evolution (HER) reactions are the most important cathodic processes involved in fuel cell and water splitting technologies, respectively. The development of bifunctional electrocatalyst materials plays a key role in the rapid advancement of these hydrogen-based renewable energy strategies. This work proposes citrate-stabilized gold nanoparticles (AuNPs) as a bifunctional electrocatalyst for ORR and HER. The capping ligand has a great influence on their resulting electrocatalytic performance. A simple ligand exchange method based on concentration gradients has been optimized. The surface structure of the different ligand-stabilized AuNPs was inferred by lead underpotential deposition (Pb-UPD). Static and dynamic electrochemical studies for both ORR and HER have been performed using different ligand-stabilized AuNPs as electrocatalysts, demonstrating that the citrate ligand confers the best performance. This work suggests that non-doped chemically synthesized AuNPs may be suitable as a bifunctional electrocatalyst in fuel cells and hydrogen production. © The Royal Society of Chemistry 2019

Correction: Tailoring the ORR and HER electrocatalytic performances of gold nanoparticles through metal-ligand interfaces (Journal of Materials Chemistry A (2019) DOI: 10.1039/c9ta05492h)

The authors regret the following minor errors in the published article. In eqn (4), a minus sign was missing from the ?nal exponential term. The correct version of eqn (4) is as follows: (Equetion Persented). © The Royal Society of Chemistry 201

Improving the electrocatalytic performance of sustainable Co/carbon materials for the oxygen evolution reaction by ultrasound and microwave assisted synthesis

The design of sustainable procedures for the preparation of cobalt/carbon-based materials as an anode for hydrogen fuel production through electrocatalytic water splitting has attracted much interest in the last few years. Herein, a novel environmentally friendly approach for the development of stable and active catalysts for the oxygen evolution reaction (OER) is reported. In detail, the methodology aimed at developing a sequence of composites having a low cobalt loading (<4%wt) using polyphenols extracted from green tea as metal stabilizers and activated carbon derived from pinecones as a metal-support as well as a co-active material. The approach exploited ultrasound (US), microwave (MW) and combined US/MW-assisted techniques with the purpose of enhancing the final electrocatalytic activity of these new composites, replacing conventional high-temperature approaches. The results indicated that the so-produced electrocatalytic materials followed the order of activity US > MW/US > MW > conventional heating, with the best sample requiring an overpotential of 365 mV to deliver a current density of 10 mA cm−2and a Tafel slope of 58 mV dec−1 © The Royal Society of Chemistry 2021

CO2 Capture with Mesoporous Silicas Modified with Amines by Double Functionalization: Assessment of Adsorption/Desorption Cycles

CO2 adsorption on mesoporous silica modified with amine by double functionalization was studied. Adsorption microcalorimetry was used in order to investigate the influence of increasing the nitrogen surface density on double functionalized materials with respect to the only grafted materials. The distribution of sites and the rate-controlling mechanism of adsorption were evaluated. A Tian Calvet microcalorimeter coupled to a manometric setup was used to evaluate the energy distribution of adsorption sites and to calculate the thermokinetic parameters from the differential enthalpy curves. CO2 and N2 adsorption equilibrium isotherms at 50 and 75 °C were measured with a magnetic suspension balance, allowing for the computation of working capacity and selectivity at two temperatures. With these data, an Adsorbent Performance Indicator (API) was calculated and contrasted with other studied materials under the same conditions. The high values of API and selectivity confirmed that double functionalized mesoporous silica is a promising adsorbent for the post combustion process. The adsorption microcalorimetric study suggests a change in active sites distribution as the amine density increases. Maximum thermokinetic parameter suggests that physisorption on pores is the rate-controlling binding mechanism for the double-functionalized material