First-principles calculation and experimental results jointly reveal that Co dopant in the Ni3S2 system not only produces the desirable ΔGH* and good HER kinetics but also lower OER energy barrier.
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•ALD combined with hydrothermal method realizes the controllable incorporation of cobalt.•The appropriate amount of cobalt is incorporated to introduce a large number of active sites.•Co-doped Ni3S2 porous nanocones display outstanding OER, HER, and overall water splitting activity.•The Co dopant in the Ni3S2 system not only produces the desirable ΔGH* and good HER kinetics but also lowers OER energy barrier.
Developing non-precious nickel-based catalysts with high activity and low cost is a big challenge for industrial alkaline water splitting. Herein, Co-doped Ni3S2 nanocones (Co12@Ni3S2/NF) are prepared by vulcanizing a cobalt oxide nanofilm on the porous nickel foam (NF) by atomic layer deposition (ALD). The electrocatalysts boast a large specific surface area, abundant active sites for rapid diffusion of electrolyte ions, fast electron transportation, and high electrochemical activity. Especially, the Co12@Ni3S2/NF electrode exhibits excellent catalytic reactivity such as a small overpotential of 62 mV to attain a current density of 10 mA cm−2 and Tafel slope of 49 mV dec−1 for HER as well as 297 mV versus RHE at 20 mA cm−2 and Tafel slope of 50.3 mV dec−1 for OER. First-principles calculations show that the proper Co dopant concentration in Ni3S2 causes large surface lattice distortion resulting in high effective ionic charge of Co atoms to greatly enhance water splitting. The strategy and materials provide insights into the design and preparation of efficient, low-cost, and durable electrodes in water splitting applications.
An ultrathin MgO coating was synthesized via atomic layer deposition (ALD) to improve the surface properties of the LiNi0.5Mn0.3Co0.2O2 (NMC) cathode. An in-situ quartz crystal sensor was used to ...monitor the “self-limiting” surface reactions during ALD process and estimate the density of the deposited film. The electrochemical performance of the MgO-coated NMC cathode was evaluated in a half-cell assembly and compared to other ALD-based coatings, such as Al2O3 and ZrO2. Cyclic voltammetry studies suggested that ALD MgO has a higher Li-diffusion coefficient which resulted in lower overpotential on the NMC cathode surface and improved Li-ion battery rate performance. MgO-coated NMC also yielded improved capacity retention over uncoated NMC in a long-range cycling test.
Surface termination and interfacial interactions are critical for advanced solid-state quantum applications. Here, in this paper, we demonstrate that atomic layer deposition (ALD) can both provide ...valuable insight on the chemical environment of the surface, having sufficient sensitivity to distinguish between the common diamond (001) surface termination types and passivate these interfaces as desired. We selected diamond substrates exhibiting both smooth and anomalously rough surfaces to probe the effect of morphology on ALD nucleation. We use high resolution in situ spectroscopic ellipsometry to monitor the surface reaction with sub-angstrom resolution, to evaluate the nucleation of an ALD Al2O3 process as a function of different ex and in situ treatments to the diamond surface. In situ water dosing and high vacuum annealing provided the most favorable environment for nucleation of dimethylaluminum isopropoxide and water ALD. Hydrogen termination passivated both smooth and rough surfaces while triacid cleaning passivated the smooth surface only, with striking effectiveness.
A first‐of‐its‐kind area‐selective deposition process for SiO2 is developed consisting of film deposition with interleaved exposures to small molecule inhibitors (SMIs) and back‐etch correction ...steps, within the same spatial atomic layer deposition (ALD) tool. The synergy of these aspects results in selective SiO2 deposition up to ~23 nm with high selectivity and throughput, with SiO2 growth area and ZnO nongrowth area. The selectivity is corroborated by both X‐ray photoelectron spectroscopy (XPS) and low‐energy ion scattering spectroscopy (LEIS). The selectivity conferred by two different SMIs, ethylbutyric acid, and pivalic acid has been compared experimentally and theoretically. Density Functional Theory (DFT) calculations reveal that selective surface functionalization using both SMIs is predominantly controlled thermodynamically, while the better selectivity achieved when using trimethylacetic acid can be explained by its higher packing density compared to ethylbutyric acid. By employing the trimethylacetic acid as SMI on other starting surfaces (Ta2O5, ZrO2, etc.) and probing the selectivity, a broader use of carboxylic acid inhibitors for different substrates is demonstrated. It is believed that the current results highlight the subtleties in SMI properties such as size, geometry, and packing, as well as interleaved back‐etch steps, which are key in developing ever more effective strategies for highly selective deposition processes.
Small molecule inhibitors (SMIs) and plasma etching are combined within the same tool for achieving area‐selective spatial atomic layer deposition of SiO2 at high‐throughput. Two SMIs using experimental and Density Functional Theory data are compared and their blocking performance in terms of size, packing density, and chemisorption energy is discussed. Low‐energy ion scattering spectroscopy demonstrates the high‐selectivity of the combined approach.
Atomic layer deposition (ALD) is a commonly used coating technique for lithium ion battery electrodes. Recently, it has been applied to sodium ion battery anode materials. ALD is known to improve the ...cycling performance, Coulombic efficiency of batteries, and maintain electrode integrity. Here, the electrochemical performance of uncoated P2-Na2/3Ni1/3Mn2/3O2 electrodes is compared to that of ALD-coated Al2O3 P2-Na2/3Ni1/3Mn2/3O2 electrodes. Given that ALD coatings are in the early stage of development for NIB cathode materials, little is known about how ALD coatings, in particular aluminum oxide (Al2O3), affect the electrode–electrolyte interface. Therefore, full characterizations of its effects are presented in this work. For the first time, X-ray photoelectron spectroscopy (XPS) is used to elucidate the cathode electrolyte interphase (CEI) on ALD-coated electrodes. It contains less carbonate species and more inorganic species, which allows for fast Na kinetics, resulting in significant increase in Coulombic efficiency and decrease in cathode impedance. The effectiveness of Al2O3 ALD coating is also surprisingly reflected in the enhanced mechanical stability of the particle which prevents particle exfoliation.
Inorganic surface coatings such as Al
O
are commonly applied on positive electrode materials to improve the cycling stability and lifetime of lithium-ion cells. The beneficial effects are typically ...attributed to the chemical scavenging of corrosive HF and the physical blockage of electrolyte components from reaching the electrode surface. The present work combines published thermochemistry data with new density functional theory calculations to propose a new mechanism of action: the spontaneous reaction of the LiPF
electrolyte salt with Al
O
-based surface coatings. Using
F and
P solution nuclear magnetic resonance spectroscopy, it is demonstrated that the storage of LiPF
-containing electrolyte solution with Al
O
produces LiPO
F
, a well-known electrolyte additive. The production of LiPO
F
is also observed for electrolyte solutions that were stored for 14 days at 40 °C with Al
O
-coated LiNi
Mn
Co
O
(NMC622) and LiNi
Co
Al
O
(NCA) materials. Given the beneficial nature of this species for the lifetime and stability of lithium-ion cells, this reaction is here proposed to similarly benefit the performance of cells that use Al
O
-coated cathode materials.
The atomic layer deposition (ALD) technique allows the synthesis of materials at the atomic scale to be controlled. ALD has been adapted to design and prepare single-atom catalysts (SACs) with ...atomic-level control. The major aim of this Review is to systematize our knowledge of the synthesis of SACs by ALD and thus help the reader to extract fundamental principles for the further development of this field. Studies of metal dimers prepared by ALD are also explored. In addition, we describe the fundamental mechanism of ALD, discuss the effects of size, shape, and metal–support interactions for catalysts, and summarize the characterization techniques and preparation methods of SACs. At the end of this Review, we present an outlook of the challenges and opportunities of the synthesis of SACs by ALD.
Self‐powered photodetectors (PDs) based on inorganic metal halide perovskites are regarded as promising alternatives for the next generation of photodetectors. However, uncontrollable film growth and ...sluggish charge extraction at interfaces directly limit the sensitivity and response speed of perovskite‐based photodetectors. Herein, by assistance of an atomic layer deposition (ALD) technique, CsPbBr3 perovskite thin films with preferred orientation and enlarged grain size are obtained on predeposited interfacial modification layers. Thanks to improved film quality and double side interfacial engineering, the optimized CsPbBr3 (Al2O3/CsPbBr3/TiO2, ACT) perovskite PDs exhibit outstanding performance with ultralow dark current of 10−11 A, high detectivity of 1.88 × 1013 Jones and broad linear dynamic range (LDR) of 172.7 dB. Significantly, excellent long‐term environmental stability (ambient conditions >100 d) and flexibility stability (>3000 cycles) are also achieved. The remarkable performance is credited to the synergistic effects of high carrier conductivity and collection efficiency, which is assisted by ALD modification layers. Finally, the ACT PDs are successfully integrated into a visible light communication system as a light receiver on transmitting texts, showing a bit rate as high as 100 kbps. These results open the window of high performance all‐inorganic halide perovskite photodetectors and extends to rational applications for optical communication.
All inorganic perovskite‐based photodetectors simultaneously achieving high responsivity, fast photoresponse, and excellent stability are achieved by assistance of an atomic layer deposition technique. Ultralow dark current of 10–11 A, high detectivity of 1.88 × 1013 Jones, broad linear dynamic range (LDR) of 172.7 dB are obtained. Moreover, the self‐powered photodetector is successfully integrated into a visible light communication system as a signal receiver.
Metal oxide semiconductor (MOS) thin films hold great promise for electronic devices such as gas sensors. However, the low surface activity of pristine MOS often leads to inferior sensitivity and the ...sensitization mechanism of ultrathin MOS films has received rare attention. Herein, we report a high performance gas sensor based on plasma-etched ZnO thin films. The ultrathin ZnO films (20 nm) were deposited on SiO2 wafers by atomic layer deposition (ALD), which enables high-throughput production of sensor devices. The ZnO sensor shows typical n-type conductivity, which is highly variable to the exposure of triethylamine (TEA). Annealing temperature of the films is found to impact the sensor response, revealing calcination at a moderate temperature, i.e. 700 °C, leads to the best response. Further treatment by Ar plasma results in a remarkable decrease of sensor working temperature from 300 °C of untreated films to 250 °C and nearly 4-fold enhancement in the sensor response to 10 ppm TEA. Notably, the plasma-treated ZnO sensor also shows decent response even at room temperature (RT), which has been seldom reported for ZnO-based sensors. Structure and mechanism investigations reveal that the superior sensor properties are derived from the abundant oxygen vacancies generated by Ar plasma etching.
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•Ultrathin ZnO films were deposited by atomic layer deposition for sensing layers.•An Ar plasma-etching strategy was developed to modulate the oxygen vacancy concentration in ZnO films.•The oxygen vacancy-rich ZnO films demonstrated attractive TEA sensing properties.•The ZnO film sensors showed nearly 4-fold enhancement in the response to 10 ppm TEA.•The plasma-treated ZnO sensor shows decent response even at room temperature (RT).
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