Energie budoucnosti a inovace

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Allotrope-dependent activity-stability relationships of molybdenum sulfide hydrogen evolution electrocatalysts
(NATURE PORTFOLIO, 2024-04-29) Escalera-López, Daniel; Iffelsberger, Christian; Zlatar, Matej; Novčić, Katarina; Maselj, Nik; Van Pham, Chuyen; Jovanovič, Primož; Hodnik, Nejc; Thiele, Simon; Pumera, Martin; Cherevko, Serhiy
Molybdenum disulfide (MoS2) is widely regarded as a competitive hydrogen evolution reaction (HER) catalyst to replace platinum in proton exchange membrane water electrolysers (PEMWEs). Despite the extensive knowledge of its HER activity, stability insights under HER operation are scarce. This is paramount to ensure long-term operation of Pt-free PEMWEs, and gain full understanding on the electrocatalytically-induced processes responsible for HER active site generation. The latter are highly dependent on the MoS2 allotropic phase, and still under debate. We rigorously assess these by simultaneously monitoring Mo and S dissolution products using a dedicated scanning flow cell coupled with downstream analytics (ICP-MS), besides an electrochemical mass spectrometry setup for volatile species analysis. We observe that MoS2 stability is allotrope-dependent: lamellar-like MoS2 is highly unstable under open circuit conditions, whereas cluster-like amorphous MoS3-x instability is induced by a severe S loss during the HER and undercoordinated Mo site generation. Guidelines to operate non-noble PEMWEs are therefore provided based on the stability number metrics, and an HER mechanism which accounts for Mo and S dissolution pathways is proposed. The stability of non-noble catalysts is key for their use in proton exchange membrane water electrolysers. Here, authors study activity-stability relationships of MoSx allotropes for H2 production, reporting allotrope-dependent stabilities and dissolution pathways, and propose operation guidelines.
Magnetic Microrobot Swarms with Polymeric Hands Catching Bacteria and Microplastics in Water
(AMER CHEMICAL SOC, 2024-05-08) Ussia, Martina; Urso, Mario; Oral, Çaatay Mert; Peng, Xia; Pumera, Martin
The forefront of micro- and nanorobot research involves the development of smart swimming micromachines emulating the complexity of natural systems, such as the swarming and collective behaviors typically observed in animals and microorganisms, for efficient task execution. This study introduces magnetically controlled microrobots that possess polymeric sequestrant "hands" decorating a magnetic core. Under the influence of external magnetic fields, the functionalized magnetic beads dynamically self-assemble from individual microparticles into well-defined rotating planes of diverse dimensions, allowing modulation of their propulsion speed, and exhibiting a collective motion. These mobile microrobotic swarms can actively capture free-swimming bacteria and dispersed microplastics "on-the-fly", thereby cleaning aquatic environments. Unlike conventional methods, these microrobots can be collected from the complex media and can release the captured contaminants in a second vessel in a controllable manner, that is, using ultrasound, offering a sustainable solution for repeated use in decontamination processes. Additionally, the residual water is subjected to UV irradiation to eliminate any remaining bacteria, providing a comprehensive cleaning solution. In summary, this study shows a swarming microrobot design for water decontamination processes.
Precision Engineering of Nanorobots: Toward Single Atom Decoration and Defect Control for Enhanced Microplastic Capture
(WILEY-V C H VERLAG GMBH, 2024-09-01) Jančík Procházková, Anna; Kmentová, Hana; Ju, Xiaohui; Kment, Štěpán; Zbořil, Radek; Pumera, Martin
Nanorobots are being received with a great attention for their move-sense-and-act capabilities that often originate from catalytic decomposition of fuels. In the past decade, single-atom engineering has demonstrated exceptional efficiency in catalysis, energy-related technologies, and medicine. Here, a novel approach involving point defect engineering and the incorporation of platinum (Pt) single atoms and atomic level species onto the surface of titanium dioxide nanotubes (TiO2-NT)-based nanorobots is presented and its impact on the propulsion capabilities of the resulting nanorobots is investigated. The achievement of point defect engineering is realized through the annealing of TiO2-NT in a hydrogen atmosphere yielding to the point-defect decorated nanotube (TiO2-HNT) nanorobots. Subsequently, the atomic level Pt species decorated TiO2 nanotube (TiO2-SA-NT) nanorobots are achieved through a wet-chemical deposition process. Whereas TiO2-SA-NT nanorobots showed the highest negative photogravitaxis when irradiated with ultraviolet (UV) light, TiO2-HNT nanorobots reached the highest velocity calculated in 2D. Both TiO2-HNT and TiO2-SA-NT nanorobots demonstrated a pronounced affinity for microplastics, exhibiting the capability to irreversibly capture them. This pioneering approach utilizing point-defect and atomic level Pt species nanorobotics is anticipated to pave the way for highly efficient solutions in the remediation of nano- and microplastics and related environmental technologies. Enhanced microplastic capture is achieved by precise engineering of TiO2-based nanorobots. The incorporation of point defects leads to the preferable schooling behavior of nanorobots in the presence of fuel and UV irradiation. On the contrary, the decoration with platinum atomic level species results in a negative photogravitaxis enabling the propulsion of nanorobots in 3D. Both designed species enabled efficient microplastics capture. image
Atomic tuning of 3D printed carbon surface chemistry for electrocatalytic nitrite oxidation and reduction to ammonia
(ROYAL SOC CHEMISTRY, 2024-11-26) Gao, Wanli; Michalička, Jan; Pumera, Martin
Nitrite contamination in agricultural and industrial wastewater presents a critical impact on environmental sustainability, demanding efficient strategies for monitoring and remediation. This study addresses this challenge by developing cost-effective electrocatalysts for both nitrite detection and conversion to value-added ammonia. 3D printed carbon materials are explored as bifunctional platforms for the electrochemical nitrite oxidation reaction (NO2OR) and nitrite reduction reaction (NO2RR). Benefiting from the inherent Ti-dominated metallic impurities and intrinsic surface features of carbon nanotubes, 3D printed carbon electrodes exhibit electrocatalytic activity for both reactions. To enhance this activity, we further introduce an effective fabrication methodology that combines 3D printing of carbon substrates with precise surface modification using atomic layer deposition (ALD) of TiO2. The resulting TiO2-coated carbon electrode demonstrates significantly improved electrocatalytic properties. For NO2OR, it exhibits a peak current density of 0.75 mA cm-2 at 1.53 V vs. RHE, while for NO2RR, it achieves a yield rate of 630.5 mu g h-1 cm-2 with a faradaic efficiency of 81.9% at -1.06 V vs. RHE. This enhancement in electrocatalytic activity is primarily attributed to the formation of abundant interfaces between the conductive carbon and ALD-coated TiO2. The developed methodology not only enables precise modification of 3D printed carbon surface chemistry but also presents a scalable method for electrocatalyst production.
Reconfigurable Magnetic Liquid Metal Microrobots: A Regenerable Solution for the Capture and Removal of Micro/Nanoplastics
(WILEY-V C H VERLAG GMBH, 2024-12-01) Wu, Xianghua; Peng, Xia; Ren, Long; Guan, Jianguo; Pumera, Martin
The pervasive presence of micro/nanoplastics in the environment is a significant threat to ecosystems and human health, demanding effective remediation strategies. Traditional methods for extracting these pollutants from water are often inadequate, typically leaving environmentally harmful residues. In response, this work introduces an innovative approach using reconfigurable and regenerable liquid metal microrobots (LiquidBots) that are magnetically driven to actively sequester micro/nanoplastics from aquatic environments. These LiquidBots utilize a coating of gallium oxide for enhanced adhesion and electrostatic interaction to capture over 80% of nanoplastics present in the solution. Additionally, the LiquidBots can be easily regenerated through sonication, which dislodges captured nanoplastics, allowing the microrobots to be reused. This novel technology offers a highly efficient, adaptable, and sustainable solution to combat the micro/nanoplastic pollution crisis. Reconfigurable and regenerable magnetic liquid metal microrobots are designed for capturing and removing micro/nanoplastics. The process involves four steps: 1) Preparation of LiquidBots. 2) Magnetic manipulation and transport of micro/nanoplastics using a 3D magnetic field. 3) Desorption of the captured micro/nanoplastics. 4) Reconfigurable of GaIn-Fe. image

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