Abstract
Negative carbon emission technologies are critical for ensuring a future stable climate. However, the gaseous state of CO
2
does render the indefinite storage of this greenhouse gas ...challenging. Herein, we created a liquid metal electrocatalyst that contains metallic elemental cerium nanoparticles, which facilitates the electrochemical reduction of CO
2
to layered solid carbonaceous species, at a low onset potential of −310 mV vs CO
2
/C. We exploited the formation of a cerium oxide catalyst at the liquid metal/electrolyte interface, which together with cerium nanoparticles, promoted the room temperature reduction of CO
2
. Due to the inhibition of van der Waals adhesion at the liquid interface, the electrode was remarkably resistant to deactivation via coking caused by solid carbonaceous species. The as-produced solid carbonaceous materials could be utilised for the fabrication of high-performance capacitor electrodes. Overall, this liquid metal enabled electrocatalytic process at room temperature may result in a viable negative emission technology.
Abstract
The predicted strong piezoelectricity for monolayers of group IV monochalcogenides, together with their inherent flexibility, makes them likely candidates for developing flexible ...nanogenerators. Within this group, SnS is a potential choice for such nanogenerators due to its favourable semiconducting properties. To date, access to large-area and highly crystalline monolayer SnS has been challenging due to the presence of strong inter-layer interactions by the lone-pair electrons of S. Here we report single crystal across-the-plane and large-area monolayer SnS synthesis using a liquid metal-based technique. The characterisations confirm the formation of atomically thin SnS with a remarkable carrier mobility of ~35 cm
2
V
−1
s
−1
and piezoelectric coefficient of ~26 pm V
−1
. Piezoelectric nanogenerators fabricated using the SnS monolayers demonstrate a peak output voltage of ~150 mV at 0.7% strain. The stable and flexible monolayer SnS can be implemented into a variety of systems for efficient energy harvesting.
Solid state dye-sensitized solar cells (sDSCs) employing the hole conductor 2,2′7,7′-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (spiro-MeOTAD) require the presence of oxygen during ...fabrication and storage. In this paper, we determine the concentrations of oxidized spiro-MeOTAD within devices under different operating and storage conditions by UV–vis spectroscopy. Relative concentrations of spiro-MeOTAD+ were found to be greater than 10% after illumination for standard sDSCs, where no chemical dopant had been used in the solar cell fabrication but oxygen and lithium ions were present. We suggest that oxidized spiro-MeOTAD is created as a byproduct of oxygen reduction at the TiO2 surface during cell illumination. Furthermore, we studied the effect of light soaking under different conditions and associated changes in spiro-MeOTAD+ concentration on the solar cell measurements. Our findings give insights to photochemical reactions occurring within sDSCs and provide guidelines for which doping levels should be used in device fabrication in absence of oxygen.
Two-dimensional (2D) transition metal oxide and chalcogenide (TMO&C)-based photocatalysts have recently attracted significant attention for addressing the current worldwide challenges of energy ...shortage and environmental pollution. The ultrahigh surface area and unconventional physiochemical, electronic and optical properties of 2D TMO&Cs have been demonstrated to facilitate photocatalytic applications. This review provides a concise overview of properties, synthesis methods and applications of 2D TMO&C-based photocatalysts. Particular attention is paid on the emerging strategies to improve the abilities of light harvesting and photoinduced charge separation for enhancing photocatalytic performances, which include elemental doping, surface functionalization as well as heterojunctions with semiconducting and conductive materials. The future opportunities regarding the research pathways of 2D TMO&C-based photocatalysts are also presented.
The properties and applications of molybdenum oxides are reviewed in depth. Molybdenum is found in various oxide stoichiometries, which have been employed for different high‐value research and ...commercial applications. The great chemical and physical characteristics of molybdenum oxides make them versatile and highly tunable for incorporation in optical, electronic, catalytic, bio, and energy systems. Variations in the oxidation states allow manipulation of the crystal structure, morphology, oxygen vacancies, and dopants, to control and engineer electronic states. Despite this overwhelming functionality and potential, a definitive resource on molybdenum oxide is still unavailable. The aim here is to provide such a resource, while presenting an insightful outlook into future prospective applications for molybdenum oxides.
Molybdenum is found in various oxide stoichiometries, which have been employed for different high‐value research and commercial applications. The variations in oxidation states allow the manipulation of crystal structure, morphology, oxygen vacancies, and dopants, to control and engineer the electronic states, which makes them versatile and highly tunable for incorporation in optical, electronic, catalytic, bio, and energy systems.
The intriguing properties of two‐dimensional transition metal dichalcogenides (2D TMDCs) have led to a significant body of fundamental research and rapid uptake of these materials in many ...applications. Specifically, 2D TMDCs have shown great potential in biological systems due to their tunable electronic characteristics, unique optical properties, stability in aqueous environments, large surface area that can be manipulated and functionalized as well as an intercalatable layered structure, and low levels of toxicity. Here, the characteristics and use of 2D TMDCs for biological applications are reviewed and future possibilities for these materials in biological systems are outlined.
Two‐dimensional transition metal dichalcogenides demonstrate a plethora of unique properties, including tunable electronic and optical characteristics, stability in aqueous environments, large surface areas that can be manipulated and functionalized, and intercalatable layered structures. Relatively low levels of toxicity and facile synthesis routes make these materials suitable for future biological systems.
Two-dimensional (2D) oxides have a wide variety of applications in electronics and other technologies. However, many oxides are not easy to synthesize as 2D materials through conventional methods. We ...used nontoxic eutectic gallium-based alloys as a reaction solvent and co-alloyed desired metals into the melt. On the basis of thermodynamic considerations, we predicted the composition of the self-limiting interfacial oxide. We isolated the surface oxide as a 2D layer, either on substrates or in suspension. This enabled us to produce extremely thin subnanometer layers of HfO₂, Al₂O₃, and Gd₂O₃. The liquid metal–based reaction route can be used to create 2D materials that were previously inaccessible with preexisting methods. The work introduces room-temperature liquid metals as a reaction environment for the synthesis of oxide nanomaterials with low dimensionality.
Nitrogen dioxide (NO2) is a gas species that plays an important role in certain industrial, farming, and healthcare sectors. However, there are still significant challenges for NO2 sensing at low ...detection limits, especially in the presence of other interfering gases. The NO2 selectivity of current gas-sensing technologies is significantly traded-off with their sensitivity and reversibility as well as fabrication and operating costs. In this work, we present an important progress for selective and reversible NO2 sensing by demonstrating an economical sensing platform based on the charge transfer between physisorbed NO2 gas molecules and two-dimensional (2D) tin disulfide (SnS2) flakes at low operating temperatures. The device shows high sensitivity and superior selectivity to NO2 at operating temperatures of less than 160 °C, which are well below those of chemisorptive and ion conductive NO2 sensors with much poorer selectivity. At the same time, excellent reversibility of the sensor is demonstrated, which has rarely been observed in other 2D material counterparts. Such impressive features originate from the planar morphology of 2D SnS2 as well as unique physical affinity and favorable electronic band positions of this material that facilitate the NO2 physisorption and charge transfer at parts per billion levels. The 2D SnS2-based sensor provides a real solution for low-cost and selective NO2 gas sensing.
Antibiotic resistance has made the treatment of biofilm-related infections challenging. As such, the quest for next-generation antimicrobial technologies must focus on targeted therapies to which ...pathogenic bacteria cannot develop resistance. Stimuli-responsive therapies represent an alternative technological focus due to their capability of delivering targeted treatment. This study provides a proof-of-concept investigation into the use of magneto-responsive gallium-based liquid metal (LM) droplets as antibacterial materials, which can physically damage, disintegrate, and kill pathogens within a mature biofilm. Once exposed to a low-intensity rotating magnetic field, the LM droplets become physically actuated and transform their shape, developing sharp edges. When placed in contact with a bacterial biofilm, the movement of the particles resulting from the magnetic field, coupled with the presence of nanosharp edges, physically ruptures the bacterial cells and the dense biofilm matrix is broken down. The antibacterial efficacy of the magnetically activated LM particles was assessed against both Gram-positive and Gram-negative bacterial biofilms. After 90 min over 99% of both bacterial species became nonviable, and the destruction of the biofilms was observed. These results will impact the design of next-generation, LM-based biofilm treatments.
It is well-understood that during the liquid-to-solid phase transition of alloys, elements segregate in the bulk phase with the formation of microstructures. In contrast, we show here that in a Bi-Ga ...alloy system, highly ordered nanopatterns emerge preferentially at the alloy surfaces during solidification. We observed a variety of transition, hybrid and crystal-defect-like patterns, in addition to lamellar and rod-like structures. Combining experiments and molecular dynamics simulations, we investigated the influence of the superficial Bi and Ga
O
layers during surface solidification and elucidated the pattern-formation mechanisms, which involve surface-catalysed heterogeneous nucleation. We further demonstrated the dynamic nature and robustness of the phenomenon under different solidification conditions and for various alloy systems. The surface patterns we observed enable high-spatial-resolution nanoscale-infrared and surface-enhanced Raman mapping, which reveal promising potential for surface- and nanoscale-based applications.
PDF
