Photoelectrochemical (PEC) water splitting, particularly self-biased PEC systems, holds great promise for solar energy utilization. However, the limited transparency of most photoelectrodes presents challenges in fabricating tandem photoelectrodes with photovoltaic (PV) cells for self-biased water splitting. Herein, a novel self-biased hybrid system integrating photoelectrodes (TiO₂, BiVO₄), beam splitters (BSs), and PV cell was proposed to enhance solar energy utilization and PEC water splitting performance. The results indicate that the integration of BSs significantly improves the current densities of both self-biased PV-PEC systems and single PEC systems. The current density of self-biased water splitting system with BSs exceeds that of the conventional TiO₂ + BVO-PV system, and the intersection point of the I–V curves for the photoanodes and solar cell is closer to the maximum power output of the solar cell. The effective utilization of the solar spectrum by both the photoelectrode and the PV cell in the hybrid system with BSs significantly increases the power output by a factor of 18.8 compared to the conventional tandem self-biased system. The predicted results indicate that the hydrogen production rate of the system with BSs is 12.1 µmol/(h·cm²), while the STH efficiency is enhanced by a factor of 12.38 and 19.87 compared to conventional TiO₂ + BVO-PV and TiO₂/BVO-PV tandem PV-PEC systems, respectively, demonstrating the advantage of the water splitting system with spectral BSs. In conclusion, this work provides an innovative approach of achieving self-biased water splitting by coupling spectral BSs with a PV-PEC system, resulting in improved solar energy harvesting efficiency.

Enzymatic biofuel cells (EBFCs), which generate electricity through electrochemical reactions between metabolites and O₂/air, are considered a promising alternative power source for wearable and implantable bioelectronics. However, the main challenges facing EBFCs are the poor stability of enzymes and the low electron transfer efficiency between enzymes and electrodes. To enhance the efficiency of EBFCs, researchers have been focusing on the development of novel functional nanomaterials. This mini-review first introduces the working principles and types of EBFCs, highlighting the key roles of nanomaterials, such as enzyme immobilization and stabilization, promotion of electron transfer and catalytic activity. It then summarizes the recent advancements in their application in wearable and implantable devices. Finally, it explores future research direction and the potential of high-performance EBFCs for practical applications.

Conventional flat-plate photovoltaic-thermal (PV-T) collectors generate electricity and heat simultaneously; however, the outlet temperature of the latter is typically below 60 °C, limiting their widespread application. The use of optical concentration can enable higher-temperature heat to be generated, but this can also lead to a rise in the operating temperature of the PV cells in the collector and, in turn, to a deterioration in their electrical performance. To overcome this challenge, an optical spectral-splitting filter that absorbs the infrared and transmits the visible portion of the solar spectrum can be used, such that wavelengths below the bandgap are sent to the cells for electricity generation, while those above it are sent to a thermally decoupled absorber for the generation of heat at a temperature that is considerably higher than that of the cells. In this study, a triangular primary PV-T channel, wherein the primary heat transfer fluid (water) flows, is integrated into a parabolic trough concentrator of geometrical concentration ratio ~10, while a secondary liquid filter (water, AgSiO₂-eg or Therminol-66) is introduced for spectral splitting. Optical, electrical and thermal-fluid (sub-)models are developed and coupled to study the performance of this collector. Each sub-model is individually checked against results taken from the literature with maximum deviations under 10%. Subsequently, the optical and electrical models are coupled with a 3-D thermal-fluid CFD model (using COMSOL Multiphysics 6.1) to predict the electrical and thermal performance of the collector. Results show that when water is used as the optical filter, the maximum overall thermal (filter channel plus primary channel) and electrical efficiencies of the collector reach ~45% and 15%, respectively. A comparison between water, AgSiO₂-eg and Therminol-66 reveals that AgSiO₂-eg improves the thermal efficiency of the filter channel by ~25% (absolute) compared to Therminol-66 and water, however, this improvement — which arises from the thermal performance of the filter — comes at an expense of a ~5% electrical efficiency loss.