A particularly alarming issue in world health today is the rise and prevalence of antibiotic-resistant bacteria, which significantly increases death rates and costs of treatment; and a group of pathogens responsible for the majority of hospital acquired infections. On 27 February 2017, WHO published list of bacteria for which new antibiotics are urgently needed. Although the Gram-positive bacteria in the ESKAPE group, including the methicillin-resistant Staphylococcus aureus, have rightly drawn attention over the past decade, infections caused by the Gram-negative microbes have recently been recognized as a more critical healthcare issue. One the other hand, detecting bacteria and other pathogenic species as well as bio-analytes like anti-oxidants, glucose, etc. is also vital.

Sensitive and selective target capture, recognition, and signal transduction in detection of chemical and biological molecules is essential for fundamental biomedical studies, disease diagnosis, and drug screening. To achieve fast, sensitive, large-scale, and low-cost molecular analysis, a wide variety of detection technologies such as fluorescent, spectroscopic, electrical, magnetic and mechanical methods have been developed.

Generally, there are three layers of complexity that are interconnected and need to be considered carefully in the development of nanomaterials for use in biomedical applications: material characteristics; interactions with biological components and biological activity outcomes. To understand and follow antibacterial and/or sensing mechanisms of nanomaterials, it is critical to know how their properties are determinant in their final performances.

To know more about fundamentals and details of the subject, some useful review papers are published like:

1- Hegab et al. The controversial antibacterial activity of graphene-based materials. Carbon, 2016.

2- Shi et al. The Antibacterial Applications of Graphene and Its Derivatives, Small, 2016.

3- Zhou et al. Applications of two-dimensional layered nanomaterials in photoelectrochemical sensors: A comprehensive review, Coordination Chemistry Reviews, 2022.

4- Tang et al. Solar-Energy-Driven Photoelectrochemical Biosensing Using TiO2 Nanowires, Chemistry, A European Journal, 2015.

5- Bai et al. Titanium Dioxide Nanomaterials for Sensor Applications, Chemical Reviews, 2014.

Useful information on this subject can be found in informative published papers like:

1- Mai et al. Machine Learning for Electrocatalyst and Photocatalyst Design and Discovery, Chemical Reviews, 2022.

2- Esterhuizen et al. Interpretable machine learning for knowledge generation in heterogeneous catalysis, Nature Catalysts, 2022.

3- Chen et al. Recent progress toward catalyst properties, performance, and prediction with data-driven methods, Current Opinion in Chemical Engineering, 2022.

4- Liu et al. Finding physical insights in catalysis with machine learning, Current Opinion in Chemical Engineering, 2022.

5- Gaviria et al. Machine learning in photovoltaic systems: A review, Renewable Energy, 2022.

6- Oviedo et al. Nanoarchitectonics: the role of artificial intelligence in the design and application of nanoarchitectures, Journal of Nanoparticle research, 2022.

Considering the depletion of hydrocarbon reservoirs and adverse effects of their combustion, providing a renewable and environmentally friendly resource of energy is necessary for human societies. Photoelectrochemical (PEC) and electrochemical (EC) water splitting into O₂ and H₂ at the surface of a proper material (photoactive semiconductor or electrocatalysts) is a promising solution to produce solar fuel as a green and sustainable source of energy. In both these approaches, each half-reaction, oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), must be optimized to achieve the highest efficiency.
The challenging step is the OER since its Gibbs free energy is 1.23 eV per electron while kinetic barriers (known as overpotential) may increase this amount up to ~2 eV. In order to reduce the overpotential, a proper electrocatalyst should be applied to facilitate surface hole transfer and raise reaction kinetics. In this context, materials employed as cocatalysts in PEC systems must be chosen among earth abundant and chemically stable compounds. According to extensive researches in this area, iridium and ruthenium-based co-catalysts are found to exhibit the lowest overpotential but not applicable due to their high cost and rarity. As proposed by well-known volcano plot, the most attracting candidates for oxygen evolution reaction are first row transition metals such as Co and Ni in the form of oxide/hydroxide nanostructures which are abundant with variety of low cost preparation methods. Recently, efficient electrocatalysts for HER are also proposed based on 2D MoS₂ nanosheets. In the following review papers, basic information about parameters as well as recent trends can be found.

1- Thorarinsdottir et l. Self-healing oxygen evolution catalysts, Nature Communications, 2022.
2- Roger et al. Earth-abundant catalysts for electrochemical and photoelectrochemical water splitting, 2017.
3- Kanan et al. Cobalt–phosphate oxygen-evolving compound, 2009.
4- Chen et al. Recent Progress on Nickel‐Based Oxide/(Oxy)Hydroxide Electrocatalysts for the Oxygen Evolution Reaction, 2018.
5- Lyu et al. Noble‐Metal‐Free Electrocatalysts for Oxygen Evolution, 2018.
6- Guo et al. Phosphate‐Based Electrocatalysts for Water Splitting: Recent Progress, 2018.
7- Zhao et al. Heterostructures for Electrochemical Hydrogen Evolution Reaction: A Review, 2018.
8- Wang et al. Recent Progress on Layered Double Hydroxides and Their Derivatives for Electrocatalytic Water Splitting, 2018.

Today, due to emerging 4^th industrial revolution (I 4.0), additive manufacturing methods for fabricating a variety of devices are very attractive. Besides different techniques like PBF, DIW, SLA, FDM, ink-jet printing (IJP) provides a powerful tool for the fabrication of functional devices with high accuracy. The operating principle of IJP technique is close to the direct ink writing (DIW) process. In these techniques, stable and homogeneous inks with desired rheological properties are formulated by dispersing active material in a liquid medium. Despite the similarities, the rheological properties of developed inks for each of these methods are different.

Here, some papers are listed as useful sources:

1- Sajedi-mogaddam et al. Inkjet-printing technology for supercapacitor application: Current state and perspectives, ACS Applied Materials and Interfaces, 2020.

2- Challagulla et al. Recent developments of nanomaterial applications in additive manufacturing: a brief review, Current Opinion in Chemical Engineering, 2020.

3- Ambrosi et al. 3D-printing for electrolytic processes and electrochemical flow systems, Journal of Materals Chemistry A, 2020.

4- Chu et al. 3D printing‐enabled advanced electrode architecture Design, Carbon energy, 2020.

5- Wang et al. Inkjet-printed flexible sensors: From function materials, manufacture process, and applications perspective, Materials Today Communications, 2022.

6- Kawale, Inkjet 3D-printing of functional layers of solid oxide electrochemical reactors: a review, Reaction Chemistry & Engineering, 2022.

Supercapacitor devices are well-known as their fast charge storage kinetics by the electric double-layer capacitance (EDLC) or EDLC-like mechanisms at the electrode/electrolyte interfaces. So far, research groups worldwide have been mostly worked on the electrodes consist of carbon-based (e.g. porous carbon, graphene, curved graphene nanosheets, graphene nanoribbons, carbide-derived carbon and etc.), two dimensional layered (e.g. Ti₃C₂T_x MXene) and transition metal oxide/sulfides/phosphates (e.g. MnO₂, Co₃O₄ and etc.) materials. The former stores charge by the adsorption of electrolyte ions onto the surface of the electrode materials providing high power density. The two latter ones store charge by fast redox reactions presenting an intrinsic (such as MnO₂) or extrinsic (such as LiCoO₂ thin films) pseudocapacitive properties providing high energy density.

More useful information on this subject can be found in informative published papers like:

1- Noori et al. Towards establishing standard performance metrics for batteries, supercapacitors and beyond, Chemical Society Reviews, 2019.

2- Bu et al. Recent developments of advanced micro-supercapacitors: design, fabrication and applications. npj Flexible Electronics, 2020.

3- Wang et al. Recent Progress in Micro-Supercapacitor Design, Integration, and Functionalization. Small Methods, 2018.

4- Gogotsi et al. Where Do Batteries End and Supercapacitors Begin? Science, 2014.

5- Brousse et al. To Be or Not To Be Pseudocapacitive? journal of the Electrochemical Society, 2015.

The alarming depletion rate of reserved fossil fuel associated with rapid increase in environmental pollution has caused an urgent need to develop efficient clean and renewable energy resources. In this regard, many different approaches have been followed up. The sun is a free, clean, sustainable and easy access energy source, and the solar produced hydrogen, which can be used in fuel cells to generate electricity or changed directly in combustion engines, makes no pollution except water. Hence, to obtain hydrogen as a clean energy carrier, the scenario of a renewable hydrogen economy has attracted much attention from researchers recently. Because of low operation temperature and strong synergies with contemporary researches in the field of photovoltaic and nanomaterials, photoelectrochemical (PEC) water splitting is an emerging technology for the future world hydrogen generation. The concept of this method is based on a semiconductor photoelectrode device which excites with sunlight irradiation, oxidizes/reduces H₂O molecules by generated h+/e− pair and finally converted them to chemical energy (H₂ gas). For efficient PEC reaction, the selected semiconductor photoanodes should exhibit chemical stability, suitable band edge positions for absorbing sunlight and also participating in water oxidation/reduction, high charge carrier mobility and also variety of low cost synthesis methods.

Photoelectrodes based on transition metal oxides, TMDCs or other emerging 2D materials have been extensively investigated in aqueous solution. Different approaches have been followed to prohibit charge recombination and improve visible response of these photoanodes.  Many interesting reports and reviews are available in this context which present recent strategies and trends to improve solar hydrogen production systems in PEC, EC or PC approaches.

1- Faraji et al. Two-dimensional materials in semiconductor photoelectrocatalytic systems for water splitting, Energy & Environmental Science, 2019.

2- Abouelela et al. Metal chalcogenide-based photoelectrodes for photoelectrochemical water splitting, Journal of Energy Chemistry, 2022.

3- Chen et al. Metal–organic frameworks and derived materials as photocatalysts for water splitting and carbon dioxide reduction, Coordination Chemistry Reviews, 2022.

4- Sharma et al. Key Strategies to Advance the Photoelectrochemical Water Splitting Performance of α‐Fe₂O₃ Photoanode, 2018. 

5- Viory et al. Low-dimensional catalysts for hydrogen evolution and CO₂ reduction, 2018.

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