• Energy Research

Microfluidic chip detection system serves as both electricity production and liquid pumping units.

Micro-sized fuel cells represent one of the pollution-free devices available to power portable electronics. However, the insufficient power output limits the possibility of micro-sized fuel cells competing with other power sources, including supercapacitors and lithium batteries. In this study, a novel aluminum-hydrogen peroxide fuel cell is fabricated using uniform silver nanowires with diameters of 0.25 µm as the catalyst at the cathode side. The Ag nanowire solution is prepared via a polyol method, and mixed uniformly with Nafion and ethanol to enhance the adhesion of Ag nanowires. We carry out electrochemical tests, including cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization, to characterize the performance of this catalyst in H2O2 reduction. The Ag nanowires exhibit a high effectiveness and durability while catalyzing the reduction of H2O2 with a low impedance. The micro-sized Al-H2O2 fuel cell equipped with Ag nanowires delivers a power density of 43 W·m−2 under a low concentration of H2O2 (0.1 M), which is substantially higher than the previously reported devices.

A laminar-flow controlled microfluidic microbial fuel cell (MMFC) is considered as a promising approach to be a bio-electrochemical system (BES). But poor bacterial colonization and low power generation are two severe bottlenecks to restrict its development. In this study, we reported a MMFC with multiple anolyte inlets (MMFC-MI) to enhance the biofilm formation and promote the power density of MMFCs. Voltage profiles during the inoculation process demonstrated MMFC-MI had a faster start-up process than the conventional microfluidic microbial fuel cell with one inlet (MMFC-OI). Meanwhile, benefited from the periodical replenishment of boundary layer near the electrode, a more densely-packed bacterial aggregation was observed along the flow direction and also the substantially low internal resistance for MMFC-MI. Most importantly, the output power density of MMFC-MI was the highest value among the reported µl-scale MFCs to our best knowledge. The presented MMFC-MI appears promising for bio-chip technology and extends the scope of microfluidic energy.

An interfacial reactor with PPCN/TiN is developed for photo–thermo-catalytic hydrogen production.

AbstractAs a reliable energy‐supply platform for wearable electronics, biosupercapacitors combine the characteristics of biofuel cells and supercapacitors to harvest and store the energy from human's sweat. However, the bulky preparation process and deep embedding of enzyme active sites in bioelectrodes usually limit the energy‐harvesting process, retarding the practical power‐supply sceneries especially during the complicated in vivo motion. Herein, a MXene/single‐walled carbon nanotube/lactate oxidase hierarchical structure as the dual‐functional bioanode is designed, which can not only provide a superior 3D catalytic microenvironment for enzyme accommodation to harvest energy from sweat, but also offers sufficient capacitance to store energy via the electrical double‐layer capacitor. A wearable biosupercapacitor is fabricated in the “island–bridge” structure with a composite bioanode, active carbon/Pt cathode, polyacrylamide hydrogel substrate, and liquid metal conductor. The device exhibits an open‐circuit voltage of 0.48 V and the high power density of 220.9 µW cm−2 at 0.5 mA cm−2. The compact conformal adhesion with skin is successfully maintained under stretching/bending conditions. After repeatedly stretching the devices, there is no significant power attenuation in pulsed output. The unique bioelectrode structure and attractive energy harvesting/storing properties demonstrate the promising potential of this biosupercapacitor as a micro self‐powered platform of wearable electronics.

To meet the emerging power demand of microelectronic and electronic skin based sensing platform, enzymatic fuel cells have received increasing attention due to their good human's compatibility, easy integration and cost effectiveness. Herein, we use multi-walled carbon nanotube/naphthoquinone to modify the lactate oxidase bio-anode to facilitate the electron transfer between electrocatalytic active site and electrode support. Polyvinyl alcohol hydrogel serves as the separator and lactate container. The bio-anode, Pt/C cathode and hydrogel are assembled in layer-by-layer structure, which can successfully utilize pre-stored and external lactate from human's sweat to generate the electricity. It delivers a power-density of 62.2 ± 2.4 μW cm-2 under bending/torsion conditions. Given that the broad substrate scope in sweat and easily assembled structure, it provides a plausible solution to power the miniaturized sensors and generic circuits.

Schematic illustration of parametric mapping in membrane-less microfluidic fuel cell (M-MFC) for performance improvement.