Mathematical modeling of overpotentials of direct glucose alkaline fuel cell and experimental validation

Theoretical study on the adsorption and oxidation of glucose on Au(111) surface

CONTEXT

While Au-based catalysts recently have shown tremendous potential in glucose oxidation to gluconic acid, the detailed reaction mechanism is still unclear, which impedes the development of direct glucose fuel cell (DGFC).

METHODS

Using density functional theory (DFT), we exhibit some new adsorption configurations and oxidation mechanisms by considering both the open chain form and the ring form of glucose on Au(111) surface in the presence of OH. The strong interactions between glucose and the OH adsorbed surface are obtained. Moreover, form the calculated energy pathways, the oxidation of glucose in the open chain involves the dissociation of the formyl C - H bond by the adsorbed OH, while the ring form glucose oxidation is initiated by O - H bond rupture rather than C - H bond scission and preferentially undergoes the ring-open process to generate the open chain form glucose. Meanwhile, the results demonstrate that the adsorbed OH assists in reducing the activation energy of reaction process.

Low-Grade Thermal Energy Harvesting and Self-Powered Sensing Based on Thermogalvanic Hydrogels

Thermoelectric cells (TEC) directly convert heat into electricity via the Seebeck effect. Known as one TEC, thermogalvanic hydrogels are promising for harvesting low-grade thermal energy for sustainable energy production. In recent years, research on thermogalvanic hydrogels has increased dramatically due to their capacity to continuously convert heat into electricity with or without consuming the material. Until recently, the commercial viability of thermogalvanic hydrogels was limited by their low power output and the difficulty of packaging. In this review, we summarize the advances in electrode materials, redox pairs, polymer network integration approaches, and applications of thermogalvanic hydrogels. Then, we highlight the key challenges, that is, low-cost preparation, high thermoelectric power, long-time stable operation of thermogalvanic hydrogels, and broader applications in heat harvesting and thermoelectric sensing.

Investigation of glucose electrooxidation mechanism over N-modified metal-doped graphene electrode by density functional theory approach

In this work, various precious and non-precious metals reported in the literature as the most effective catalysts for glucose electrooxidation reaction were investigated by the density functional theory (DFT) approach in order to reveal the mechanisms taking place over the catalysts in the fuel cell. The use of a single-atom catalyst model was adopted by insertion of one Au, Cu, Ni, Pd, Pt, and Zn metal atom on the pyridinic N atoms doped graphene surface (NG). β form of d-glucose in alkaline solution was used to determine the reaction mechanism and intermediates that formed during the reaction. DFT results showed that the desired glucono-lactone was formed on the Cu-3NG electrode in a single-step reaction pathway whereas it was produced via different two-step pathways on the Au and Pt-3NG electrodes. Although the interaction of glucose with Ni, Pd, and Zn-doped surfaces resulted in the deprotonation of the molecule, lactone product formation did not occur on these electrode surfaces. When the calculation results are evaluated in terms of energy content and product formation, it can be concluded that Cu, Pt, and especially Au doped graphene catalysts are effective for direct glucose oxidation in fuel cells reactor.

Enhancement of ethanol-oxygen biofuel cell output using a CNT based nano-composite as bioanode

The present research, describes preparation and application of a novel bioanode for ethanol-oxygen biofuel cells. We applied an enzyme based nanocomposite consisting of polymethylene green as electron transfer mediator, carboxylated-multiwall carbon nanotubes as electron transfer accelerator, alcohol dehydrogenase as biocatalyst and polydiallyldimethylammonium chloride as supporting agent. In the presence of β-nicotinamide adenine dinucleotide as cofactor, and ethanol as fuel, the feasibility of the bioanode for increasing the power was evaluated under the ambient conditions. In the optimum conditions the biofuel cell produced the power density of 1.713 mW cm(-2) and open circuit voltage of 0.281 V.