Nanostructured Inorganic Materials at Work in Electrochemical Sensing and Biofuel Cells

Abstract

Abstract:The future of analytical devices, namely (bio)sensors, which are currently impacting our everyday life, relies on several metrics such as low cost, high sensitivity, good selectivity, rapid response, real-time monitoring, high-throughput, easy-to-make and easy-to-handle properties. Fortunately, they can be readily fulfilled by electrochemical methods. For decades, electrochemical sensors and biofuel cells operating in physiological conditions have concerned biomolecular science where enzymes act as biocatalysts. However, immobilizing them on a conducting substrate is tedious and the resulting bioelectrodes suffer from stability. In this contribution, we provide a comprehensive, authoritative, critical, and readable review of general interest that surveys interdisciplinary research involving materials science and (bio)electrocatalysis. Specifically, it recounts recent developments focused on the introduction of nanostructured metallic and carbon-based materials as robust "abiotic catalysts" or scaffolds in bioelectrochemistry to boost and increase the current and readout signals as well as the lifetime. Compared to biocatalysts, abiotic catalysts are in a better position to efficiently cope with fluctuations of temperature and pH since they possess high intrinsic thermal stability, exceptional chemical resistance and long-term stability, already highlighted in classical electrocatalysis. We also diagnosed their intrinsic bottlenecks and highlighted opportunities of unifying the materials science and bioelectrochemistry fields to design hybrid platforms with improved performance.

Advances in Electrocatalysis for Energy Conversion and Synthesis of Organic Molecules

“…Again, after two periods (1960–1980 and 2000‐now) of intense experimental high‐throughput screening of electrode materials,, there is still not a single BFC in use. Deliberately, we do not examine herein this topic; those who are interested can refer to a recent review paper that diagnoses the efficiency of nanostructured inorganic materials at work in electrochemical sensing and biofuel cells . Then, the majority of investigators base their efforts almost exclusively on the use and a thorough understanding of the reaction mechanisms of Pt, Au and Pd catalysts, which are the most capable of performing the reaction at a low anode potential.…”

“…It should be noted that the experimental conditions for fuel cell tests do not enable a rational comparison with the literature because electrocatalytic inks were deposited on glassy carbon (surface area of the fuel cell is 0.071 cm 2 , loading information not available) as anode and cathode electrodes. As previously explained, when the output power is intended to be normalized with the geometric surface area of the electrode in terms of mW cm −2 , the size of the limiting electrode should be at least superior to 0.5–1 cm 2 for trustworthiness and to avoid any conflicting comparison. For instance, a claimed high‐power‐density fuel cell (expressed in milliwatt per square centimeter, mW cm −2 ) that involves an electrode size lesser than one square centimeter (<1 cm 2 ) won't be necessarily the best‐performing when one employs a larger electrode surface for the simple reason that “ P max vs. electrode surface” is not a perfect linear relationship.…”

Fuel Cells and Biofuel Cells: From Past to Perspectives

“…Overall, significant increase in size and, therefore, power production, of the enzyme‐based biofuel cells is not possible. The research in the enzyme biofuel cells (also including “abiotic” biofuel cells based on inorganic catalytic materials instead of enzymes [73] ) is mostly directed to their miniaturization, sometimes to extremely small sizes, particularly aiming at their implantable design for in vivo use. Figure 12A shows a micro‐size electrocatalytic electrode suggested for future implantable operation in human brain extracting power from cerebrospinal fluid [74] .…”

Functionalization of Carbon Nanomaterials for Biomedical Applications

“…One of the most important biosensors is for the detection of glucose because it plays very important role in the diagnosis and therapy of diabetes. In recent years, great effort has been devoted to the third-generation glucose sensor, which can overcome the sensing dependence on dissolved oxygen in the first-generation sensors and the need of mediates in the second-generation sensors [63]. Same as the former two generations, glucose oxidase (GOx) with a flavin adenine dinucleotide (FAD) as cofactor is used to react with glucose in biological samples, with glucose oxidized by GOx into gluconic acid while GOx(FAD) reduced into GOx(FADH 2 ).…”