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Surface modification of cellulosic paper is demonstrated by employing plasma assisted atomic layer deposition. Al2O3 thin films are deposited on paper substrates, prepared with different fiber sizes, to improve their barrier properties. Thus, a hydrophobic paper is created with low gas permeability by combining the control of fiber size (and structure) with atomic layer deposition of Al2O3 films. Papers are prepared using Kraft softwood pulp and thermomechanical pulp. The cellulosic wood fibers are refined to obtain fibers with smaller length and diameter. Films of Al2O3, 10, 25, and 45 nm in thickness, are deposited on the paper surface. The work demonstrates that coating of papers prepared with long fibers efficiently reduces wettability with slight enhancement in gas permeability, whereas on shorter fibers, it results in significantly lower gas permeability. Wettability studies on Al2O3 deposited paper substrates have shown water wicking and absorption over time only in papers prepared with highly refined fibers. It is also shown that there is a certain fiber size at which the gas permeability assumes its minimum value, and further decrease in fiber size will reverse the effect on gas permeability.

A highly efficient adsorbent containing a Cu-BTC/CuO/CFP composite with a microporous copper benzene–1,3,5-tricarboxylate/CuO coating on a macroporous carbon fiber paper was designed via atomic layer deposition with the synthesis time of 6 h. The existing moderate CuO in Cu-BTC/CuO/CFP forms micropores between CuO and Cu-BTC and CuO and CFP to promote selectivity of CH4/N2. The effects of synthesis time and CuO content on the selectivity of CH4/N2 and effective thermal conductivity were experimentally investigated. The pressure drop and adsorption rate of the adsorption bed and temperature response of the desorption bed were numerically predicted. The selectivity of equimolar CH4/N2 for Cu-BTC/CuO/CFP (0.30 : 0.13 : 0.57) (6 h) is 2.15–2.65 times higher than that of pure Cu-BTC. The Cu-BTC/CuO/CFP material has higher effective thermal conductivity, lower pressure drop, higher adsorption rate, and better temperature uniformity compared to pure Cu-BTC powder in the adsorption bed.

Large-scale growth of low-cost, efficient, and durable non-noble metal-based electrocatalysts for water splitting is crucial for future renewable energy systems. Atomic layer deposition (ALD) provides a promising route for depositing uniform thin coatings of electrocatalysts, which are useful in many technologies, including the splitting of water. In this communication, we report the growth of a NiO/Ni catalyst directly on carbon fiber paper by atomic layer deposition and report subsequent reduction and oxidation annealing treatments. The 10–20 nm NiO/Ni nanoparticle catalysts can reach a current density of 10 mA·cm−2 at an overpotential of 189 mV for hydrogen evolution reactions and 257 mV for oxygen evolution reactions with high stability. We further successfully achieved a water splitting current density of 10 mA·cm−2 at 1.78 V using a typical NiO/Ni coated carbon fiber paper two-electrode setup. The results suggest that nanoparticulate NiO/Ni is an active, stable, and noble-metal-free electrocatalyst, which facilitates a method for future water splitting applications.

Acid degradation of cellulosic paper in archival books, periodicals, and historic documents is a serious and widespread problem. Using acidic page samples from ∼40 year old books, we demonstrate that atomic layer deposition (ALD) ZnO can adjust and controllably neutralize the paper acid content. The paper samples were collected and analyzed in accordance with recognized Technical Association of the Pulp and Paper Industry (TAPPI) test standards. The average pH of the starting paper was 3.7 ± 0.4 and 4.4 ± 0.1 as determined using the TAPPI surface probe and cold water extraction methods, respectively. After 50 ALD ZnO cycles, the same tests on the coated paper produced an average pH of 7.39 ± 0.08 and 7.3 ± 0.4, respectively. Scanning electron microscopy confirmed that the cellulose structure remained intact during ALD. Additional tests of recently printed newspaper samples coated with ALD ZnO also show that ALD can effectively prevent paper discoloration and embrittlement caused by UV sunlight photoexposure. While there are many known methods for paper preservation, including others using diethyl zinc, the control afforded by ALD provides attractive advantages over other known approaches for preservation of archival paper and other natural fibrous materials.

Atomic Layer Deposition (ALD) was used to grow single-crystalline epitaxial layers of high-k dielectric oxides on semiconductors with remarkably few defects or traps at the interfaces. La 2 O 3 on GaAs(111) produced record-breaking transistors with both n-and p-channels, and CMOS circuits entirely in GaAs, including inverters, logic circuits and 5-stage ring oscillators. More conventionally oriented GaAs(100) substrates with etched (111) slopes also produced working transistors. ALD also grew single-crystalline epitaxial La 2 O 3 films on Ge(111), and (Ca, Mg)O films on GaN(0001) substrates with high-quality epitaxial interfaces. These processes can be run in commercial ALD reactors using precursors produced by the Dow Chemical Company.

Two new atomic/molecular layer deposition processes for depositing crystalline metal‐organic thin films, built from 1,4‐benzenedisulfonate (BDS) as the organic linker and Cu or Li as the metal node, are reported. The processes yield in‐situ crystalline but hydrated Cu‐BDS and Li‐BDS films; in the former case, the crystal structure is of a previously known metal‐organic‐framework‐like structure, while in the latter case not known from previous studies. Both hydrated materials can be readily dried to obtain the crystalline unhydrated phases. The stability and the ionic conductivity of the unhydrated Li‐BDS films were characterized to assess their applicability as a thin film solid polymer Li‐ion conductor., A new organic linker for atomic/molecular layer depositions (ALD/MLD) was demonstrated with copper and lithium metal nodes. The films are crystalline with and without water of crystallization. The applicability of dilithium‐1,4‐benzenedisulfonate as a solid polymer ion conductor is assessed.

Chemistry - a European journal 27(38), 9791-9800 (2021). doi:10.1002/chem.202101126, Multilayered heterostructures comprising of In$_2$O$_3$, SnO$_2$, and Al$_2$O$_3$ were studied for their application in thin-film transistors (TFT). The compositional influence of tin oxide on the properties of the thin-film, as well as on the TFT characteristics is investigated. The heterostructures are fabricated by atomic layer deposition (ALD) at 200 °C, employing trimethylindium (TMI), tetrakis(dimethylamino)tin (TDMASn), trimethylaluminum (TMA), and water as precursors. After post-deposition annealing at 400 °C the thin-films are found to be amorphous, however, they show a discrete layer structure of the individual oxides of uniform film thickness and high optical transparency in the visible region. Incorporation of only two monolayers of Al$_2$O$_3$ in the active semiconducting layer the formation of oxygen vacancies can be effectively suppressed, resulting in an improved semiconducting and switching behavior. The heterostacks comprising of In$_2$O$_3$/SnO$_2$/Al$_2$O$_3$ are incorporated into TFT devices, exhibiting a saturation field-effect mobility ($μ_{sat}$) of 2.0 cm$^2$⋅ V$^{−1}$ s$^{−1}$, a threshold-voltage (V$_{th}$) of 8.6 V, a high current on/off ratio (I$_{On}$/I$_{Off}$) of 1.0×10$^7$, and a subthreshold swing (SS) of 485 mV ⋅ dec$^{−1}$. The stability of the TFT under illumination is also altered to a significant extent. A change in the transfer characteristic towards conductive behavior is evident when illuminated with light of an energy of 3.1 eV (400 nm)., Published by Wiley-VCH, Weinheim

Today, silicon solar cells (amorphous films and wafer-based) are a main source of green energy. These cells and their components are produced by employing various technologies. Unfortunately, during the production process, chemicals that are harmful for the environment and for human life are used. For example, hydrofluoric acid is used to texture the top electrode to improve light harvesting. In this work, and also in recent ones, we report a way to obtain 3D textures on the top electrode by using zinc oxide nanorods. The efficiency of a textured solar cell structure is compared with the one obtained for a planar zinc oxide/silicon structure. The present results show the possibility to produce efficient solar cells on a relatively thin 50 μm thick silicon substrate. Solar cells with structured top electrodes were examined by numerous measuring techniques. Scanning electron microscopy revealed a grain-like morphology of the magnesium-doped zinc oxide film. The size of the grains is closely related to the structure of the nanorods. The external quantum efficiency of the cells was measured. The obtained solar cell shows response in a wide spectral range from ultraviolet to infrared. Current–voltage and current–voltage–temperature measurements were performed to evaluate basic photovoltaic parameters. At room temperature, the cells efficiency equals to 9.1% for textured structures and 5.4% for planar structures, respectively. The work, therefore, describes an environmentally friendly technology for PV architecture with surface textures increasing the efficiency of PV cells.

Al2O3 layers were deposited onto electrodes by atomic layer deposition. Solubility and electron-transport blocking were tested. Films deposited onto fluorine-doped tin oxide (FTO, F:SnO2/glass) substrates blocked electron transfer to redox couples (ferricyanide/ferrocyanide) in aqueous media. However, these films were rapidly dissolved in 1 M NaOH (≈100 nm/h). The dissolution was slower in 1 M H2SO4 (1 nm/h) but after 24 h the blocking behaviour was entirely lost. The optimal stability was reached at pH 7.2 where no changes were found up to 24 h and even after 168 h of exposure the changes in the blocking behaviour were still minimal. This behaviour was also observed for protection against direct reduction of FTO.

Metal carbides are promising materials for electrocatalytic reactions such as water electrolysis. However, for application in catalysis for the oxygen evolution reaction (OER), protection against oxidative corrosion, a high surface area with facile electrolyte access, and control over the exposed active surface sites are highly desirable. This study concerns a new method for the synthesis of porous tungsten carbide films with template‐controlled porosity that are surface‐modified with thin layers of nickel oxide (NiO) to obtain active and stable OER catalysts. The method relies on the synthesis of soft‐templated mesoporous tungsten oxide (mp. WO x ) films, a pseudomorphic transformation into mesoporous tungsten carbide (mp. WC x ), and a subsequent shape‐conformal deposition of finely dispersed NiO species by atomic layer deposition (ALD). As theoretically predicted by density functional theory (DFT) calculations, the highly conductive carbide support promotes the conversion of Ni2+ into Ni3+, leading to remarkably improved utilization of OER‐active sites in alkaline medium. The obtained Ni mass‐specific activity is about 280 times that of mesoporous NiO x (mp. NiO x ) films. The NiO‐coated WC x catalyst achieves an outstanding mass‐specific activity of 1989 A gNi −1 in a rotating‐disc electrode (RDE) setup at 25 °C using 0.1 m KOH as the electrolyte., ALD‐fashioned: A highly active and stable electrocatalyst for the alkaline oxygen evolution reaction based on a mesoporous tungsten carbide film surface‐modified with a conformal NiO layer by atomic layer deposition is presented. The electrocatalyst reaches a record high mass activity of 1989 A gNi −1 in 0.1 m KOH electrolyte, which is more than 280 times higher than that of a mesoporous NiO x film.

We investigated the use of dielectric layers produced by atomic layer deposition (ALD) as an approach to strain mitigation in composite silicon/superconductor devices operating at cryogenic temperatures. We show that the addition of an ALD layer acts to reduce the strain of spins closest to silicon/superconductor interface where strain is highest. We show that appropriately biasing our devices at the hyperfine clock transition of bismuth donors in silicon, we can remove strain broadening and that the addition of ALD layers left T 2 (or temporal inhomogeneities) unchanged in these natural silicon devices.

The search for and synthesis of new antimicrobial nanostructures is important to reduce microbial incidence that induces infectious diseases and to aid in the antibiotic resistance crisis, which are two of the most pressing issues in global public health. In this work, novel, hollow, calcined titanium dioxide nanospheres (CSTiO2) were successfully synthesized for the first time through the combination of electrospinning and atomic layer deposition techniques. Poly(vinylpyrrolidone) (PVP) electrosprayed spherical particles were double-coated with alumina and titanium dioxide, and after a calcination process, hollow nanospheres were obtained with a radius of approximately 345 nm and shell thickness of 17 nm. The structural characterization was performed using electron microscopy, and X-ray diffraction and small-angle X-ray diffraction evidenced an anatase titanium dioxide crystalline structure. Thermogravimetric analysis and Fourier-transform infrared spectroscopy studies demonstrated the absence of polymer residue after the calcination process. The antimicrobial properties of the developed CSTiO2 hollow nanospheres were evaluated against different bacteria, including resistant E. coli and S. aureus strains, and when compared to commercial TiO2 nanoparticles, CSTiO2 nanospheres exhibited superior performance. In addition, the positive effect of UV irradiation on the antimicrobial activity was demonstrated.

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial ultra-thin catalyst films under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function analysis., Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm–50 nm crystalline indium tin oxide or a 100 nm–150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure–function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.

Lithiated thin films are necessary for the fabrication of novel solid-state batteries, including the electrodes and solid electrolytes. Physical vapour deposition and chemical vapour deposition can be used to deposit lithiated films. However, the issue of conformality on non-planar substrates with large surface area makes them impractical for nanobatteries the capacity of which scales with surface area. Atomic layer deposition (ALD) avoids these issues and is able to deposit conformal films on 3D substrates. However, ALD is limited in the range of chemical reactions, due to the required volatility of the precursors. Moreover, relatively high temperatures are necessary (above 100 °C), which can be detrimental to electrode layers and substrates, for example to silicon into which the lithium can easily diffuse. In addition, several highly reactive precursors, such as Grignard reagents or n-butyllithium (BuLi) are only usable in solution. In theory, it is possible to use BuLi and water in solution to produce thin films of LiH. This theoretical reaction is self-saturating and, therefore, follows the principles of solution atomic layer deposition (sALD). Therefore, in this work the sALD technique and principles have been employed to experimentally prove the possibility of LiH deposition. The formation of homogeneous air-sensitive thin films, characterized by using ellipsometry, grazing incidence X-ray diffraction (GIXRD), in situ quartz crystal microbalance, and scanning electron microscopy, was observed. Lithium hydride diffraction peaks have been observed in as-deposited films by GIXRD. X-ray photoelectron spectroscopy and Auger spectroscopy analysis show the chemical identity of the decomposing air-sensitive films. Despite the air sensitivity of BuLi and LiH, making many standard measurements difficult, this work establishes the use of sALD to deposit LiH, a material inaccessible to conventional ALD, from precursors and at temperatures not suitable for conventional ALD.

We have constructed thin films of organic–inorganic hybrid character by combining titanium tetra-isopropoxide (TTIP) and the nucleobases thymine, uracil or adenine using the molecular layer deposition (MLD) approach. Such materials have potential as bioactive coatings, and the bioactivity of these films is described in our recent work [Momtazi, L.; Dartt, D. A.; Nilsen, O.; Eidet, J. R. J. Biomed. Mater. Res., Part A 2018, 106, 3090–3098. doi:10.1002/jbm.a.36499]. The growth was followed by in situ quartz crystal microbalance (QCM) measurements and all systems exhibited atomic layer deposition (ALD) type of growth. The adenine system has an ALD temperature window between 250 and 300 °C, while an overall reduction in growth rate with increasing temperature was observed for the uracil and thymine systems. The bonding modes of the films have been further characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction, confirming the hybrid nature of the as-deposited films with an amorphous structure where partial inclusion of the TTIP molecule occurs during growth. The films are highly hydrophilic, while the nucleobases do leach in water providing an amorphous structure mainly of TiO2 with reduced density and index of refraction.

Although 2D layered nanomaterials have been intensively investigated towards their application in energy conversion and storage devices, their disadvantages have rarely been explored so far especially compared to their 3D counterparts. Herein, WO3·nH2O (n = 0, 1, 2), as the most common and important electrochemical and electrochromic active nanomaterial, is synthesized in 3D and 2D structures through a facile hydrothermal method, and the disadvantages of the corresponding 2D structures are examined. The weakness of 2D WO3·nH2O originates from its layered structure. X-ray diffraction and scanning electron microscopy analyses of as-grown WO3·nH2O samples suggest a structural transition from 2D to 3D upon temperature increase. 2D WO3·nH2O easily generates structural instabilities by 2D intercalation, resulting in a faster performance degradation, due to its weak interlayer van der Waals forces, even though it outranks the 3D network structure in terms of improved electronic properties. The structural transformation of 2D layered WO3·nH2O into 3D nanostructures is observed via ex situ Raman measurements under electrochemical cycling experiments. The proposed degradation mechanism is confirmed by the morphology changes. The work provides strong evidence for and in-depth understanding of the weakness of 2D layered nanomaterials and paves the way for further interlayer reinforcement, especially for 2D layered transition metal oxides.

In order to effectively utilize the photovoltaic properties of gallium arsenide, its surface/interface needs to be properly prepared. In the experiments described here we examined eight different paths of GaAs surface treatment (cleaning, etching, passivation) which resulted in different external quantum efficiency (EQE) values of the tested photovoltaic (PV) cells. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) examinations were conducted to obtain structural details of the devices. X-ray photoelectron spectroscopy (XPS) with depth profiling was used to examine interface structure and changes in the elemental content and chemical bonds. The photoluminescence (PL) properties and bandgap measurements of the deposited layers were also reported. The highest EQE value was obtained for the samples initially etched with a citric acid-based etchant and, in the last preparation step, either passivated with ammonium sulfide aqueous solution or treated with ammonium hydroxide solution with no final passivation. Subsequent I–V measurements, however, confirmed that from these samples, only the sulfur-passivated ones provided the highest current density. The tested devices were fabricated by using the ALD method.

Beilstein journal of nanotechnology 11, 952-959 (2020). doi:10.3762/bjnano.11.79, Published by Beilstein-Institut zur Förderung der Chemischen Wissenschaften, Frankfurt, M.

In this work we modelled the diffusive transport of a dilute gas along arrays of randomly distributed, vertically aligned nanocylinders (nanotubes or nanowires) as opposed to gas diffusion in long pores, which is described by the well-known Knudsen theory. Analytical expressions for (i) the gas diffusion coefficient inside such arrays, (ii) the time between collisions of molecules with the nanocylinder walls (mean time of flight), (iii) the surface impingement rate, and (iv) the Knudsen number of such a system were rigidly derived based on a random-walk model of a molecule that undergoes memoryless, diffusive reflections from nanocylinder walls assuming the molecular regime of gas transport. It can be specifically shown that the gas diffusion coefficient inside such arrays is inversely proportional to the areal density of cylinders and their mean diameter. An example calculation of a diffusion coefficient is delivered for a system of titanium isopropoxide molecules diffusing between vertically aligned carbon nanotubes. Our findings are important for the correct modelling and optimisation of gas-based deposition techniques, such as atomic layer deposition or chemical vapour deposition, frequently used for surface functionalisation of high-aspect-ratio nanocylinder arrays in solar cells and energy storage applications. Furthermore, gas sensing devices with high-aspect-ratio nanocylinder arrays and the growth of vertically aligned carbon nanotubes need the fundamental understanding and precise modelling of gas transport to optimise such processes.

Atomically thin semiconducting oxide on graphene carries a unique combination of wide band gap, high charge carrier mobility, and optical transparency, which can be widely applied for optoelectronics. However, study on the epitaxial formation and properties of oxide monolayer on graphene remains unexplored due to hydrophobic graphene surface and limits of conventional bulk deposition technique. Here, we report atomic scale study of heteroepitaxial growth and relationship of a single-atom-thick ZnO layer on graphene using atomic layer deposition. We demonstrate atom-by-atom growth of zinc and oxygen at the preferential zigzag edge of a ZnO monolayer on graphene through in situ observation. We experimentally determine that the thinnest ZnO monolayer has a wide band gap (up to 4.0 eV), due to quantum confinement and graphene-like structure, and high optical transparency. This study can lead to a new class of atomically thin two-dimensional heterostructures of semiconducting oxides formed by highly controlled epitaxial growth.

Plasmonic metal/semiconductor composites have attracted great attention for efficient solar energy harvesting in photovoltaic and photocatalytic applications owing to their extremely high visible-light absorption and tuned effective band gap. In this work, Ag-loaded TiO2 nanocolumn (Ag-TNC) arrays were fabricated based on anodic aluminum oxide (AAO) template by combining atomic layer deposition (ALD) and vacuum evaporation. The effects of the Ag loading position and deposition thickness, and the morphology, structure and composition of Ag-deposited TNC arrays on its optical and photocatalytic properties were studied. The Ag-filled TiO2 (AFT) nanocolumn arrays exhibited higher removal efficiency of methylene blue (MB) compared with Ag-coated TiO2 (ACT) nanocolumn arrays and pure TiO2 nanocolumns arrays. Both experimental and theoretical simulation results demonstrated that the enhanced photocatalytic performance of AFT nanocolumn arrays was attributed to the surface plasmon resonance (SPR) of Ag and the absorption of light by TiO2. These results represent a promising step forward to the development of high-performance photocatalysts for energy conversion and storage.

The synthesis of nanoporous ZnO thin films is achieved through annealing of zinc-alkoxide (“zincone”-like) layers obtained by plasma-enhanced atomic layer deposition (PE-ALD). The zincone-like layers are deposited through sub-saturated PE-ALD adopting diethylzinc and O2 plasma with doses below self-limiting values. Nanoporous ZnO thin films were subsequently obtained by calcination of the zincone-like layers between 100–600 °C. Spectroscopic ellipsometry (SE) and X-ray diffraction (XRD) were adopted in situ during calcination to investigate the removal of carbon impurities, development of controlled porosity, and formation and growth of ZnO crystallites. The layers developed controlled nanoporosity in the range of 1–5%, with pore sizes between 0.27 and 2.00 nm as measured with ellipsometric porosimetry (EP), as a function of the plasma dose and post-annealing temperature. Moreover, the crystallinity and crystallite orientation could be tuned, ranging from a powder-like to a (100) preferential growth in the out-of-plane direction, as measured by synchrotron-radiation grazing incidence XRD. Calcination temperature ranges were identified in which pore formation and subsequent crystal growth occurred, giving insights in the manufacturing of nanoporous ZnO from Zn-based hybrid materials.

Commercially available metal inks are mainly designed for planar substrates (for example, polyethylene terephthalate foils or ceramics), and they contain hydrophobic polymer binders that fill the pores in fabrics when printed, thus resulting in hydrophobic electrodes. Here, a low‐cost binder‐free method for the metallization of woven and nonwoven fabrics is presented that preserves the 3D structure and hydrophilicity of the substrate. Metals such as Au, Ag, and Pt are grown autocatalytically, using metal salts, inside the fibrous network of fabrics at room temperature in a two‐step process, with a water‐based silicon particle ink acting as precursor. Using this method, (patterned) metallized fabrics are being enabled to be produced with low electrical resistance (less than 3.5 Ω sq−1). In addition to fabrics, the method is also compatible with other 3D hydrophilic substrates such as nitrocellulose membranes. The versatility of this method is demonstrated by producing coil antennas for wireless energy harvesting, Ag–Zn batteries for energy storage, electrochemical biosensors for the detection of DNA/proteins, and as a substrate for optical sensing by surface enhanced Raman spectroscopy. In the future, this method of metallization may pave the way for new classes of high‐performance devices using low‐cost fabrics.

In the planar perovskite solar cells (PSCs), the electron transport layer (ETL) plays a critical role in electron extraction and transport. Widely utilized TiO2 ETLs suffer from the low conductivity and high surface defect density. To address these problems, for the first time, two types of ETLs based on TiO2 phase junction are designed and fabricated distributed in the opposite space, namely anatase/rutile and rutile/anatase. The champion efficiency of PSCs based on phase junction ETL is over 15%, which is much higher than that of cells with single anatase (9.8%) and rutile (11.8%) TiO2 as ETL. The phase junction based PSCs also demonstrated obviously reduced hysteresis. The enhanced performance is discussed and mainly ascribed to the excellent capability of carrier extraction, defect passivation, and reduced recombination at the ETL/perovskite interface. This work opens a new phase junction ETL strategy toward interfacial energy band manipulation for improved PSC performance.

In this work, carbon-coated NiO nanoparticles supported on graphene (NiO@C/graphene) have been synthesized by integrating an atomic layer deposition (ALD) technique with a simple acetylene decomposition method. Transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy and Raman results demonstrated that uniform carbon films were coated onto the surfaces of NiO nanoparticles supported on graphene. The electrochemical properties of the NiO@C/graphene were then investigated. The results showed that the special design enabled synergistic effects from graphene and the carbon layer to improve the electrochemical capacitive properties of NiO. As a supercapacitor electrode, the 400-NiO@C/graphene exhibits an initial specific capacitance of 408 F g−1 (1838 F g−1 for NiO) at 1 A g−1 and 68% is retained at 50 A g−1. After 2000 charge–discharge cycles, the specific capacitance improves the initial value of ∼28% at a high current density of 10 A g−1, suggesting a great potential for high performance supercapacitors.

Integrating metals and metal oxides with graphene is key in utilizing its extraordinary material properties that are ideal for nanoelectronic and catalyst applications. Atomic layer deposition (ALD) has become a key technique for depositing ultrathin, conformal metal(oxide) films. ALD of metal(oxide) films on graphene, however, remains a genuine challenge due to the chemical inertness of graphene. In this study we address this issue by combining first-principles density functional theory (DFT) simulations with ALD experiments. The focus is on the Pt ALD on graphene, as this hybrid system is very promising for solar and fuel cells, hydrogen technologies, microreactors, and sensors. Here we elucidate the surface reactions underpinning the nucleation stage of Pt ALD on pristine, defective and functionalized graphenes. The employed reaction mechanism clearly depends on (a) the available surface groups on graphene, and (b) the ligands accompanying the metal centre in the precursor. DFT calculations also indicate that graphene oxide (GO) can afford a stronger adsorption of MeCpPtMe3, unlike Pt(acac)2, as compared to bare (non-functionalized) graphene, suggesting that GO monolayers are effective Pt ALD seed layers. Confirming the latter, we evince that wafer-scale, continuous Pt films can indeed be grown on GO monolayers using a thermal ALD process with MeCpPtMe3 and O2 gas. Besides, the current in-depth atomistic insights are of practical use for understanding similar ALD processes of other metals and metal oxides on graphene.