Hydrogen-oxidizing bacteria (HOB) have been shown to be promising micro-organisms for the reduction of carbon dioxide to a wide range of value-added products in bioelectrochemical systems with in situ water electrolysis of the cultivation medium, also known as a hybrid biological-inorganic systems (HBI). However, scaling up of this process requires overcoming the inherent constraints of the low energy efficiency partly associated with the pH-neutral electrolyte with low conductivity. Most of the research in the field is concentrated on the bacterial cultivation, whereas the analysis and evaluation of the electrode material performance have received little attention in the literature so far. Therefore, in the present work, in situ electrolysis of a pH-neutral medium for HOB cultivation was performed with different combinations of electrode materials. Besides conventional electrode types, electrodes with coatings made of earth-abundant cobalt and a nickel-iron alloy, known for their catalytic activity for the kinetically sluggish oxygen evolution reaction (OER), were prepared and tested as potential substitutes for catalysts made of precious metals. The cultivation of HOB with in situ water electrolysis has been successfully tested in a small scale electrobioreactor in order to support the experimental results. A simplified water electrolysis model was developed and applied to evaluate the current-voltage characteristics of an bioelectrochemical system prototype. Application of the developed model allows quantitative evaluation and comparison of reversible, ohmic, and activation overvoltages of different electrode sets. The modeling results were found to agree well with the experimental data. The developed model and the data gathered can be applied to further investigation, simulation, and optimization of HBI systems.

The worldwide spread of the SARS-CoV-2 virus has continued to accelerate, putting a considerable burden on public health, safety, and the global economy. Taking into consideration that the main route of virus transmission is via respiratory particles, the face mask represents a simple and efficient barrier between potentially infected and healthy individuals, thus reducing transmissibility per contact by reducing transmission of infected respiratory particles. However, long-term usage of a face mask leads to the accumulation of significant amounts of different pathogens and viruses onto the surface of the mask and can result in dangerous bacterial and viral co-infections. Zeolite imidazolate framework-8 (ZIF-8) has recently emerged as an efficient water-stable photocatalyst capable of generating reactive oxygen species under light irradiation destroying dangerous microbial pathogens. The present study investigates the potential of using ZIF-8 as a coating for face masks to prevent the adherence of microbial/viral entities. The results show that after 2 h of UV irradiation, a polypropylene mask coated with ZIF-8 nanostructures is capable of eliminating S. Aureus and bacteriophage MS2 with 99.99% and 95.4% efficiencies, respectively. Furthermore, low-pathogenic HCoV-OC43 coronavirus was eliminated by a ZIF-8-modified mask with 100% efficiency already after 1 h of UV irradiation. As bacteriophage MS2 and HCoV-OC43 coronavirus are commonly used surrogates of the SARS-CoV-2 virus, the revealed antiviral properties of ZIF-8 can represent an important step in designing efficient protective equipment for controlling and fighting the current COVID-19 pandemic.

Hydrogen-oxidizing bacteria provide a sustainable solution for microbial protein production. Renewable electricity can be used for in situ water electrolysis in an electrobioreactor. The use of cultivation medium as the electrolyte enhances the hydrogen dissolution to the medium. This paper proposes a stack structure for in situ water electrolysis to improve the productivity of the electrobioreactor. The hydrogen production rate and the energy efficiency of the prototype stack are analyzed.

Metal-organic frameworks (MOFs), with their highly coordinated structure, high porosity, and tunability have piqued vast scientific attention as a promising platform for creating high-efficiency electrocatalysts for water electrolysis. However, the conventional methods of creating MOF-derived electrocatalysts are time- and energy-consuming and often lead to significant aggregation of metal particles and the formation of non-homogeneous porous structures. In this research, we leverage the potential of the MOF-template-directed fabrication approach, combined with microwave heating and laser-assisted post-treatment, to develop a facile, scalable, and versatile strategy for electrocatalyst synthesis. Specifically, hierarchically structured Ni-based MOF-74 was rapidly synthesized from the Ni hydroxide nanosheet arrays deposited onto a Ni foam substrate using microwave-assisted synthesis. Subsequently, the obtained structures were treated using a focused laser to create MOF-74(Ni)-derived composite electrocatalyst featuring encapsulated nickel oxide nanoparticles. The resulting electrocatalyst exhibited high efficiency and stability for facilitating the oxygen evolution reaction (OER) under alkaline conditions. The outstanding electrocatalytic performance of the developed material enables it to reach a current density of 50 mA cm⁻² at an overpotential of 318 mV. High electrocatalytic activity can be attributed to its distinctive morphology, which offers numerous exposed active sites for water splitting. The experimental data gathered in this study is anticipated to be of significant value for the synthesis of other MOF-derived composite materials featuring hierarchical structures. Furthermore, the study emphasized the importance of using a combination of microwave heating and laser-assisted post-treatment of MOFs to achieve a sustainable and efficient process for electrocatalyst synthesis.