Atomic Layer Deposition of Electrocatalytic Insulator Al2O3 on Three-Dimensional Printed Nanocarbons

Additive Manufacturing: A Paradigm Shift in Revolutionizing Catalysis with 3D Printed Photocatalysts and Electrocatalysts Toward Environmental Sustainability

Semiconductor-based materials utilized in photocatalysts and electrocatalysts present a sophisticated solution for efficient solar energy utilization and bias control, a field extensively explored for its potential in sustainable energy and environmental management. Recently, 3D printing has emerged as a transformative technology, offering rapid, cost-efficient, and highly customizable approaches to designing photocatalysts and electrocatalysts with precise structural control and tailored substrates. The adaptability and precision of printing facilitate seamless integration, loading, and blending of diverse photo(electro)catalytic materials during the printing process, significantly reducing material loss compared to traditional methods. Despite the evident advantages of 3D printing, a comprehensive compendium delineating its application in the realm of photocatalysis and electrocatalysis is conspicuously absent. This paper initiates by delving into the fundamental principles and mechanisms underpinning photocatalysts electrocatalysts and 3D printing. Subsequently, an exhaustive overview of the latest 3D printing techniques, underscoring their pivotal role in shaping the landscape of photocatalysts and electrocatalysts for energy and environmental applications. Furthermore, the paper examines various methodologies for seamlessly incorporating catalysts into 3D printed substrates, elucidating the consequential effects of catalyst deposition on catalytic properties. Finally, the paper thoroughly discusses the challenges that necessitate focused attention and resolution for future advancements in this domain.

Comparative Study of Plasma-Enhanced-Atomic-Layer-Deposited Al2O3/HfO2/SiO2 and HfO2/Al2O3/SiO2 Trilayers for Ultraviolet Laser Applications

High-performance thin films combining large optical bandgap Al2O3 and high refractive index HfO2 are excellent components for constructing the next generation of laser systems with enhanced output power. However, the growth of low-defect plasma-enhanced-atomic-layer-deposited (PEALD) Al2O3 for high-power laser applications and its combination with HfO2 and SiO2 materials commonly used in high-power laser thin films still face challenges, such as how to minimize defects, especially interface defects. In this work, substrate-layer interface defects in Al2O3 single-layer thin films, layer-layer interface defects in Al2O3-based bilayer and trilayer thin films, and their effects on the laser-induced damage threshold (LIDT) were investigated via capacitance-voltage (C-V) measurements. The experimental results show that by optimizing the deposition parameters, specifically the deposition temperature, precursor exposure time, and plasma oxygen exposure time, Al2O3 thin films with low defect density and high LIDT can be obtained. Two trilayer anti-reflection (AR) thin film structures, Al2O3/HfO2/SiO2 and HfO2/Al2O3/SiO2, were then prepared and compared. The trilayer AR thin film with Al2O3/HfO2/SiO2 structure exhibits a lower interface defect density, better interface bonding performance, and an increase in LIDT by approximately 2.8 times. We believe these results provide guidance for the control of interface defects and the design of thin film structures and will benefit many thin film optics for laser applications.

Carbon Black Integrated Polylactic Acid Electrodes Obtained by Fused Deposition Modeling: A Powerful Tool for Sensing of Sulfanilamide Residues in Honey Samples

Sulfanilamide (SFL) is used to prevent infections in honeybees. However, many regulatory agencies prohibit or establish maximum levels of SFL residues in honey samples. Hence, we developed a low-cost and portable electrochemical method for SFL detection using a disposable device produced through 3D printing technology. In the proposed approach, the working electrode was printed using a conductive filament based on carbon black and polylactic acid and it was associated with square wave voltammetry (SWV). Under optimized SWV parameters, linear concentration ranges (1-10 μmol L^-1 and 12.5-35.0 μmol L^-1), a detection limit of 0.26 μmol L^-1 (0.05 mg L^-1), and suitable RSD values (2.4% for inter-electrode; n = 3) were achieved. The developed method was selective in relation to other antibiotics applied in honey samples, requiring only dilution in the electrolyte. The recovery values (85-120%) obtained by SWV were statistically similar (95% confidence level) to those obtained by HPLC, attesting to the accuracy of the analysis and the absence of matrix interference.

Polyoxometalate-Enhanced 3D-Printed Supercapacitors

The contemporary critical energy crisis demands the fast and cost-effective preparation of supercapacitors to replace old-fashioned batteries. 3D-printing has been established as a fast, cheap, and reliable new manufacturing technique that enables the preparation of such devices.. Unfortunately, carbon-based filaments used in 3D printing lack the necessary electrical properties to build supercapacitors by themselves and have to be combined with other materials to reach their full potential. In this study, carbon-based 3D-printed carbon electrodes (3D-PCE) have been combined with two polyoxometalates (that share the same redox cluster) by drop casting of the inorganic cluster mixed with a conducting slurry. The modified electrodes show higher capacitances than reference carbon electrodes showing the exceptional properties of the polyoxometalates. Moreover, the different nature of the polyoxometalate counter ions allows for their distinct deposition, giving rise to a different coverage of the surface of the 3D-PCE. The different coverage and the nature of the interaction of the counter ion with the electrolyte significantly modify the capacitance and resistance of the materials, playing a key role that should not be overlooked during their preparation.

Integrating Structural Colors with Additive Manufacturing Using Atomic Layer Deposition

We demonstrate tunable structural color patterns that span the visible spectrum using atomic layer deposition (ALD). Asymmetric metal-dielectric-metal structures were sequentially deposited with nickel, zinc oxide, and a thin copper layer to form an optical cavity. The color response was precisely adjusted by tuning the zinc oxide (ZnO) thickness using ALD, which was consistent with model predictions. Owing to the conformal nature of ALD, this allows for uniform and tunable coloration of non-planar three-dimensional (3D) objects, as exemplified by adding color to 3D-printed parts produced by metal additive manufacturing. Proper choice of inorganic layered structures and materials allows the structural color to be stable at elevated temperatures, in contrast to traditional paints. To print multiple colors on a single sample, polymer inhibitors were patterned in a desired geometry using electrohydrodynamic jet (e-jet) printing, followed by area-selective ALD in the unpassivated regions. The ability to achieve 3D color printing, both at the micro- and macroscales, provides a new pathway to tune the optical and aesthetic properties during additive manufacturing.

Hierarchical Atomic Layer Deposited V2 O5 on 3D Printed Nanocarbon Electrodes for High-Performance Aqueous Zinc-Ion Batteries

Aqueous rechargeable zinc-ion batteries (ARZIBs) are promising energy storage systems owing to their ecofriendliness, safety, and cost-efficiency. However, the sluggish Zn²⁺ diffusion kinetics originated from its inherent large atomic mass and high polarization remains an ongoing challenge. To this end, electrodes with 3D architectures and high porosity are highly desired. This work reports a rational design and fabrication of hierarchical core-shell structured cathodes (3D@V₂ O₅ ) for ARZIBs by integrating fused deposition modeling (FDM) 3D-printing with atomic layer deposition (ALD). The 3D-printed porous carbon network provides an entangled electron conductive core and interconnected ion diffusion channels, whereas ALD-coated V₂ O₅ serves as an active shell without sacrificing the porosity for facilitated Zn²⁺ diffusion. This endows the 3D@V₂ O₅ cathode with high specific capacity (425 mAh g^-1 at 0.3 A g^-1 ), competitive energy and power densities (316 Wh Kg^-1 at 213 W kg^-1 and 163 Wh Kg^-1 at 3400 W kg^-1 ), and good rate performance (221 mAh g^-1 at 4.8 A g^-1 ). The developed 3D@V₂ O₅ cathode provides a promising model for customized and scalable battery electrode engineering technology. As the ALD-coated layer determines the functional properties, the proposed strategy shows a promising prospect of FDM 3D printing using 1D carbon materials for future energy storage.

3D-Printed COVID-19 immunosensors with electronic readout

3D printing technology has brought light in the fight against the COVID-19 global pandemic event through the decentralized and on-demand manufacture of different personal protective equipment and medical devices. Nonetheless, since this technology is still in an early stage, the use of 3D-printed electronic devices for antigen test developments is almost an unexplored field. Herein, a robust and general bottom-up biofunctionalization approach via surface engineering is reported aiming at providing the bases for the fabrication of the first 3D-printed COVID-19 immunosensor prototype with electronic readout. The 3D-printed COVID-19 immunosensor was constructed by covalently anchoring the COVID-19 recombinant protein on a 3D-printed graphene-based nanocomposite electrode surface. The electrical readout relies on impedimetrically monitoring changes at the electrode/electrolyte interface after interacting with the monoclonal COVID-19 antibody via competitive assay, fact that hinders the redox conversion of a benchmark redox marker. Overall, the developed 3D-printed system exhibits promising electroanalytical capabilities in both buffered and human serum samples, displaying an excellent linear response with a detection limit at trace levels (0.5 ± 0.1 μg·mL^-1). Such achievements demonstrate advantage of light-of-speed distribution of 3D printing datafiles with localized point-of-care low-cost printing and bioelectronic devices to help contain the spread of emerging infectious diseases such as COVID-19. This technology is applicable to any post-COVID-19 SARS diseases.

Covalently modified enzymatic 3D-printed bioelectrode

Three-dimensional (3D) printing has showed great potential for the construction of electrochemical sensor devices. However, reported 3D-printed biosensors are usually constructed by physical adsorption and needed immobilizing reagents on the surface of functional materials. To construct the 3D-printed biosensors, the simple modification of the 3D-printed device by non-expert is mandatory to take advantage of the remote, distributed 3D printing manufacturing. Here, a 3D-printed electrode was prepared by fused deposition modeling (FDM) 3D printing technique and activated by chemical and electrochemical methods. A glucose oxidase-based 3D-printed nanocarbon electrode was prepared by covalent linkage method to an enzyme on the surface of the 3D-printed electrode to enable biosensing. X-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the glucose oxidase-based biosensor. Direct electrochemistry glucose oxidase-based biosensor with higher stability was then chosen to detect the two biomarkers, hydrogen peroxide and glucose by chronoamperometry. The prepared glucose oxidase-based biosensor was further used for the detection of glucose in samples of apple cider. The covalently linked glucose oxidase 3D-printed nanocarbon electrode as a biosensor showed excellent stability. This work can open new doors for the covalent modification of 3D-printed electrodes in other electrochemistry fields such as biosensors, energy, and biocatalysis.

Versatile Design of Functional Organic-Inorganic 3D-Printed (Opto)Electronic Interfaces with Custom Catalytic Activity

The ability to combine organic and inorganic components in a single material represents a great step toward the development of advanced (opto)electronic systems. Nowadays, 3D-printing technology has generated a revolution in the rapid prototyping and low-cost fabrication of 3D-printed electronic devices. However, a main drawback when using 3D-printed transducers is the lack of robust functionalization methods for tuning their capabilities. Herein, a simple, general and robust in situ functionalization approach is reported to tailor the capabilities of 3D-printed nanocomposite carbon/polymer electrode (3D-nCE) surfaces with a battery of functional inorganic nanoparticles (FINPs), which are appealing active units for electronic, optical and catalytic applications. The versatility of the resulting functional organic-inorganic 3D-printed electronic interfaces is provided in different pivotal areas of electrochemistry, including i) electrocatalysis, ii) bio-electroanalysis, iii) energy (storage and conversion), and iv) photoelectrochemical applications. Overall, the synergism of combining the transducing characteristics of 3D-nCEs with the implanted tuning surface capabilities of FINPs leads to new/enhanced electrochemical performances when compared to their bare 3D-nCE counterparts. Accordingly, this work elucidates that FINPs have much to offer in the field of 3D-printing technology and provides the bases toward the green fabrication of functional organic-inorganic 3D-printed (opto)electronic interfaces with custom catalytic activity.

3D Printing Temperature Tailors Electrical and Electrochemical Properties through Changing Inner Distribution of Graphite/Polymer

The rise of 3D printing technology, with fused deposition modeling as one of the simplest and most widely used techniques, has empowered an increasing interest for composite filaments, providing additional functionality to 3D-printed components. For future applications, like electrochemical energy storage, energy conversion, and sensing, the tuning of the electrochemical properties of the filament and its characterization is of eminent importance to improve the performance of 3D-printed devices. In this work, customized conductive graphite/poly(lactic acid) filament with a percentage of graphite filler close to the conductivity percolation limit is fabricated and 3D-printed into electrochemical devices. Detailed scanning electrochemical microscopy investigations demonstrate that 3D-printing temperature has a dramatic effect on the conductivity and electrochemical performance due to a changed conducive filler/polymer distribution. This may allow, e.g., 3D printing of active/inactive parts of the same structure from the same filament when changing the 3D printing nozzle temperature. These tailored properties can have profound influence on the application of these 3D-printed composites, which can lead to a dramatically different functionality of the final electrical, electrochemical, and energy storage device.