Raney-platinum thin film electrodes for the catalysis of glucose in abiotically catalyzed micro-glucose fuel cells

Abstract

Fuel cells capabable of synthetic glucose catalysis have revolved around the implementation of abiotic catalysts that require extreme acid and alkaline environments. These are not compatible with implantable medical sensor systems, and hence there is a need to develop abiotic catalysts that operate at neutral pH. This paper presents structural and electrochemical characteristics of a nanoporous electrode designed for abiotic glucose oxidation in the presence of oxygen in neutral physiological media. The electrode was fabricated by annealing e-beam deposited thin films of Platinum (Pt) and Nickel (Ni) into a Pt-Ni alloy on a silicon substrate. The porous nature of the alloy enhance electrochemical properties by increasing the real surface area ~ 500 times compared to the geometric surface area of as-prepared multilayer thin films. This was reflected in the exchange current density of the electrode annealed at 800 C being twice that of the electrode annealed at 650 C. The cell voltage increase, due to the addition of dissolved physiological oxygen of 2 ppm, was about 100 ± 8 mV under a load current density of 2 µA cm-2. After running for 72 hours in a physiological saline solution with 5 mM glucose, the increase in the electrode potential was only 23 µV h 1 . These results suggest that the nanoporous Pt-Ni alloy anode offers an improved catalytic stability with time and should be a viable candidate for use in abiotic catalysed glucose fuel cell systems operating under physiological conditions.

Pt Concave Nanocubes with High-Index Facets as Electrocatalysts for Glucose Oxidation

“…With the more positive potential applied, the electrode surface becomes less adsorptive. 40,44 In this region, abundant OH ads species generate due to the fast decomposition of water and the subsequent adsorption of the hydroxide anion, which is consistent with the "Incipient Hydrous Oxide Adatom Mediator" model (IHOAM) proposed by Burke. 45 The reactive OH ads premonolayer formed at the metal active sites on the electrode surface is catalytic to the oxidation of the adsorbed glucose.…”

“…Once the platinum oxide (PtO) film is created, the glucose molecules are directly oxidized on the PtO layer, and the poisoning product of lactone type is decomposed by further oxidation . During the reverse scan of CV, negligible glucose oxidation occurs at 0.55 V, which directly follows the Pt oxide reduction at about 0.77 V . As shown in Figure b, no obvious redox peaks can be observed on Pt CNC and commercial Pt/C (10 wt.…”

“…In eq , S H is the adsorption peak area of hydrogen, V is the scanning speed, M Pt is the mass of platinum on the working electrode surface (g), and 0.21 (mC cm –2 ) is the charge density of Pt. − The ECSA of Pt CNCs is calculated to be 1.58 m 2 g –1 . The defect structures, such as atomic steps, kinks, and edges, derived from the high-index (510) facets of Pt CNCs maximize the surface area-to-mass ratio.…”

The Synthesis of Carbon Black-Loaded Pt Concave Nanocubes with High-Index Facets and Their Enhanced Electrocatalytic Properties toward Glucose Oxidation

“…The ECSA value is evaluated by integrating the peak area of the CV scanning, performed in a nitrogen-saturated 0.5 M H 2 SO 4 solution with a scan rate of 50 mV s −1 . The charge was normalized using a surface area-specific charge of an ideal one-electron transfer, which is 210 μC cm −2 [ 37 , 38 ]. As shown in Figure 4 a, the peak area of Pt CNC/CB was larger than that of the Pt CNC catalyst.…”

Synthesis of Carbon Black Loaded Pt Concave Nanocubes with High-Index Facets and their Enhanced Electrocatalytic Properties toward Glucose Oxidation

“…The ECSA value is evaluated by integrating the peak area of the CV scanning, performed in the nitrogen-saturated 0.5 M H2SO4 solution with a scan rate of 50 mV s −1 . The charge is normalized using a surface area-specific charge of an ideal one-electron transfer, which is 210 μC cm −2 [35,36]. As shown in Figure 4a, the peak area of Pt CNC/CB is larger than that of Pt CNC catalyst.…”