One-Compartment InGaN Nanowire Fuel Cell in the Light and Dark Operating Modes

Hydrogen peroxide photo-fuel cells

Hydrogen peroxide (H2O2) possesses both strong oxidizing and moderate reducing ability. Due to the unique chemical reactivity, one-compartmentalization of fuel cells is possible by using H2O2 as both the fuel and oxidant for fuel cells (H2O2-FC). To enhance the anode reaction (H2O2 → O2 + 2H+ + 2e-) of the H2O2-FC, a noble metal-free H2O2-photo fuel cell (PFC) has been newly developed for enhancing the conversion from chemical energy to electric energy with only emission of water and oxygen. The H2O2-photo fuel cells (PFC) take several significant advantages over the conventional hydrogen-oxygen fuel cells. With the realization of a solar-driven energy cycle with H2O2 as the key substance in mind, this Frontier article highlights the H2O2-PFCs. Firstly, the fundamentals of the H2O2-PFC are dealt with by treating the prototype using TiO2 as the photoanode. Then, recent progress in the H2O2-PFCs and an emerging application to self-powered biosensors are described. Finally, the conclusions are summarized with the future outlook.

InN/InGaN Quantum Dot Abiotic One-Compartment Glucose Photofuel Cell: Power Supply and Sensing

InN/InGaN quantum dots (QDs) are introduced as an efficient photoanode for a novel abiotic one-compartment photofuel cell (PFC) with a Pt cathode and glucose as a biofuel. Due to the high catalytic activity and selectivity of the InN/InGaN QDs toward oxidation reactions, the PFC operates without a membrane under physiologically mild conditions at medium to low glucose concentrations with a noble-metal-free photoanode. A relatively high short-circuit photocurrent density of 0.56 mA/cm² and a peak output power density of 0.22 mW/cm² are achieved under 1 sun illumination for a 0.1 M glucose concentration with optimized InN/InGaN QDs of the right size. The super-linear dependence of the short-circuit photocurrent density and the output power density as a function of the logarithmic glucose concentration makes the PFC well suited for sensing, covering the 4-6 mM range of glucose concentration in blood under normal conditions with good selectivity. No degradation of the PFC operation over time is observed.