Hematite is a classical photoanode material for photoelectrochemical water splitting due to its stability, performance, and low cost. However, the effect of particle size is still a question due to the charge transfer to the electrodes. In this work, we addressed this subject by the fabrication of a photoelectrode with hematite nanoparticles embedded in close contact with the electrode substrate. The nanoparticles were synthesized by a solvothermal method and colloidal stabilization with charged hydroxide molecules, and we were able to further use them to prepare electrodes for water photo-oxidation. Hematite nanoparticles were embedded within electrospun tin-doped indium oxide nanofibers. The fibrous layer acted as a current collector scaffold for the nanoparticles, supporting the effective transport of charge carriers. This method allows better contact of the nanoparticles with the substrate, and also, the fibrous scaffold increases the optical density of the photoelectrode. Electrodes based on nanofibers with embedded nanoparticles display significantly enhanced photoelectrochemical performance compared to their flat nanoparticle-based layer counterparts. This nanofiber architecture increases the photocurrent density and photon-to-current internal conversion efficiency by factors of 2 and 10, respectively.

Background: The outbreak of COVID-19 pandemic highlighted the necessity for accessible and affordable medical ventilators for healthcare providers. To meet this challenge, researchers and engineers world-wide have embarked on an effort to design simple medical ventilators that can be easily distributed. This study provides a simulation model of a simple one-sensor controlled, medical ventilator system including a realistic lungs model and the synchronization between a patient breathing and the ventilator. This model can assist in the design and optimization of these newly developed systems. Methods: The model simulates the ventilator system suggested and built by the “Manshema” team which employs a positive-pressure controlled system, with air and oxygen inputs from a hospital external gas supply. The model was constructed using Simscape™ (MathWorks®) and guidelines for building an equivalent model in OpenModelica software are suggested. The model implements an autonomously breathing, realistic lung model, and was calibrated against the ventilator prototype, accurately simulating the ventilator operation. Results: The model allows studying the expected gas flow and pressure in the patient’s lungs, testing various control schemes and their synchronization with the patient’s breathing. The model components, inputs, and outputs are described, an example for a simple, positive end expiratory pressure control mode is given, and the synchronization with healthy and ARDS patients is analyzed. Conclusions: We provide a simulator of a medical ventilation including realistic, autonomously breathing lungs model.  The simulator allows testing different control schemes for the ventilator and its synchronization with a breathing patient. Implementation of this model may assist in efforts to develop simple and accessible medical ventilators to meet the global demand.