Showing papers in "Materials horizons in 2017"

Searching for promising new perovskite-based photovoltaic absorbers: the importance of electronic dimensionality

Abstract: Searching for promising nontoxic and air-stable perovskite absorbers for solar cell applications has drawn extensive attention. Here, we show that a promising perovskite absorber should exhibit a high electronic dimensionality. Semiconductors that exhibit a high structural dimensionality, but a low electronic dimensionality have less promise as an absorber, because of barriers to isotropic current flow, enhanced electron/hole effective masses and fundamentally deeper defect states (more effective at causing recombination). Our concept accounts for the device performance of the perovskite-based solar cells reported in literature so far.

Thermoresponsive polymers with lower critical solution temperature: from fundamental aspects and measuring techniques to recommended turbidimetry conditions

Abstract: Thermoresponsive polymers that undergo reversible phase transition by responding to an environmental temperature change, in particular polymers showing lower critical solution temperature (LCST), are frequently used as smart materials that have found increasing applications. Recently, there has been a rapid growth in interest on LCST polymers and many new research groups are entering the field from a wide range of application areas. While it is great to see more researchers working on LCST polymers, the downside of this rapid growth is that the fundamentals of the LCST phase transition behavior are not always clearly known and respected. Hence, this focus article provides a systematic discussion of the key aspects of the LCST behavior of polymers starting from fundamentals of LCST behavior to practical determination of cloud point temperature (Tcp). Finally, we offer a basic set of recommended measuring conditions for determination of Tcp (10 mg mL−1; 0.5 °C min−1; 600 nm) to facilitate the comparison of the LCST behavior and Tcp values of polymers developed and studied in different laboratories around the globe, which is nowadays nearly impossible since various techniques and parameters are being utilized for the measurements. It should be noted that these recommended conditions serve as a robust tool for turbidimetry, which is one out of the many characterization techniques one should utilize to fully understand LCST behavior of polymers.

Metal organic framework based catalysts for CO2 conversion

Abstract: Metal organic frameworks (MOFs) are hybrid crystalline materials, exhibiting high specific surface areas, controllable pore sizes and surface chemistry. These properties have made MOFs attractive for a wide range of applications including gas separation, gas storage, sensing, drug delivery and catalysis. This review focuses on recent progress in the application of MOF materials as catalysts for CO2 conversion through chemical fixation, photocatalysis and electrocatalysis. In particular, this review discusses the co-relationship between the physicochemical properties of MOF materials including their catalytic performance as well as their stability and recyclability under different reaction conditions, relevant to CO2 conversion. Current modification techniques for improving MOF performance are highlighted along with the recent understanding of their electronic properties. The limitations of MOF based catalysts are also discussed and potential routes for improvement are suggested.

Recyclable 3D printing of vitrimer epoxy

Abstract: 3D printing of polymeric materials for various applications has been quickly developed in recent years. In contrast to thermoplastics, 3D printed thermosets, although desirable, are inherently non-recyclable due to their permanently crosslinked networks. As 3D printing is becoming more popular, it is desirable to develop recycling approaches for 3D printed parts in view of increasing polymer wastes. Here, we present a new thermosetting vitrimer epoxy ink and a 3D printing method that can 3D print epoxy into parts with complicated 3D geometries, which later can be recycled into a new ink for the next round of 3D printing. In the first printing cycle, a high-viscous ink is first slightly cured and is then printed at an elevated temperature into complicated 3D structures, followed by an oven cure using a two-step approach. To be recycled, the printed epoxy parts are fully dissolved in an ethylene glycol solvent in a sealed container at a high temperature. The dissolved polymer solution is reused for the next printing cycle using similar printing conditions. Our experiments demonstrate that the ink can be printed four times and still retains very good printability. In addition, the vitrimer epoxy can be used for pressure-free repairs for the 3D printed parts.

Optimal sound-absorbing structures

Abstract: The causal nature of the acoustic response dictates an inequality that relates the two most important aspects of sound absorption: the absorption spectrum and the sample thickness. We use the causality constraint to delineate what is ultimately possible for sound absorbing structures, and denote those which can attain near-equality for the causality constraint to be “optimal.” Anchored by the causality relation, a design strategy is presented for realizing structures with target-set absorption spectra and a sample thickness close to the minimum value as dictated by causality. By using this approach, we have realized a 10.86 cm-thick structure that exhibits a broadband, near-perfect flat absorption spectrum starting at around 400 Hz, while the minimum sample thickness from the causality constraint is 10.36 cm. To illustrate the versatility of the approach, two additional optimal structures with different target absorption spectra are presented. This “absorption by design” strategy would enable the tailoring of customized solutions to difficult room acoustic and noise remediation problems.

Recent advances in black phosphorus-based photonics, electronics, sensors and energy devices

Abstract: In the past several years, two-dimensional black phosphorus (BP) has captured the research community's interest because of its unique electronic, photonic, and mechanical properties. Remarkable efforts have been made regarding the synthesis, fundamental understanding, and applications of BP in the fields of nanoelectronics, nanophotonics, and optoelectronics. In this review, we summarize the recent developments in the study of BP, which covers the state-of-the-art synthesis methods for preparing single-layer or few-layer BP, the recent advances in characterizing its electronic, optical and mechanical properties, and the reported functional devices utilizing such properties. Finally we discuss the existing challenges in developing BP-based nanoelectronics and optoelectronics, and describe the prospects for future BP-related research.

Designing Indirect-Direct Bandgap Transitions in Double Perovskites

Abstract: A general design strategy is presented for tuning the convergence of direct and indirect bandgaps based on chemical adjustment of the s- and p-orbital character of the conduction band minimum To demonstrate the viability of the design strategy, we successfully synthesized a family of double perovskites: Cs2AgSbCl6 with an indirect bandgap and Cs2AgInCl6 with a direct bandgap and the solid solutions between the two

Metal–organic frameworks: a novel host platform for enzymatic catalysis and detection

Abstract: The use of metal–organic frameworks (MOFs) as immobilization matrices for enzymes as a platform for emerging applications is reported. In addition to an overview of strategies developed to prepare enzyme–MOF biocomposites, the features that render MOFs interesting matrices for bio-immobilization are highlighted along with their potential benefits beyond a solid-state support in the design of innovative biocomposites.

3D network of cellulose-based energy storage devices and related emerging applications

Abstract: There has recently been a major thrust toward advanced research in the area of hierarchical carbon nanostructured electrodes derived from cellulosic resources, such as cellulose nanofibers (CNFs), which are accessible from natural cellulose and bacterial cellulose (BC). This research is providing a firm scientific basis for recognizing the inherent mechanical and electrochemical properties of those composite carbon materials that are suitable for carbon-electrode applications, where they represent obvious alternatives to replace the current monopoly of carbon materials (carbon nanotubes, reduced graphene oxide, and their derivatives). Significant promising developments in this area are strengthened by the one dimensional (1D) nanostructures and excellent hydrophobicity of the CNFs, the interconnected pore networks of carbon aerogels, and the biodegradable and flexible nature of cellulose paper and graphenic fibers. Outstanding electrode materials with different dimensions (1D, 3D) are derivable by the strategic choice of cellulose sources. This development requires special attention in terms of understanding the significant impact of the cellulose morphology on the final electrochemical performance. This review article attempts to emphasize the role of the different structural forms and corresponding composites derived from different forms of cellulose, including bacterial cellulose and its varied 3D nanostructures. This article strongly highlights that cellulose deserves special attention as an extremely abundant and extensively recyclable material that can serve as a source of components for electronic and energy devices. Along with emphasizing current trends in electrochemical device components from cellulose, we address a few emerging areas that may lead in future such as enzyme immobilization, flexible electronics, modelling of cellulosic microfibrils. Finally, we have discussed some of the important future prospects for cellulose as source of materials for future.

Recent advances in air electrodes for Zn–air batteries: electrocatalysis and structural design

Abstract: Zn–air batteries have attracted significant attention because of their high energy density, environmental friendliness, safety, and low cost. The air cathode of is one of the most expensive cell components and a key factor in determining the performance of Zn–air batteries. As a fuel, O2 availability to the air cathode is determined by the level of both its dissolution and diffusion in an electrolyte, whereby electrocatalysis happens in the three-phase interface where the catalyst, electrolyte, and O2 meet. Maximizing the performance of air cathodes by rational design of the catalyst structure is of significant importance. To date, various electrocatalysts, including heteroatom-doped carbon, transition metal nitrides/oxides/sulfides, and perovskite oxides, have been developed with outstanding oxygen reduction reaction and oxygen evolution activity. More and more researchers are trying to apply electrocatalysts into Zn–air battery prototypes. The aim of this review is to afford a better understanding of air cathodes and provide guidelines to the researchers for the design and construction of high-performance, easy-to-use cathodes for metal–air batteries.

Nanoparticle/MOF composites: preparations and applications

Abstract: Over the last twenty years, MOFs have emerged as a new promising porous material in the areas of gas sorption and separation, catalysis, drug delivery, and molecule sensing. Moreover, nanomaterials have also attracted widespread attention in recent years. Owing to the porous structure of MOFs, we can combine nanoparticles with MOFs to obtain nanoparticle/MOF composites, which possess the advantages of both parent materials. In the present study, we utilized two main methods to introduce nanoparticles into MOFs: a method employing MOFs as templates to hold guest nanoparticles in their channels and a method employing the encapsulation of pre-synthesized nanoparticles. The former includes chemical vapor deposition, solid grinding, liquid impregnation, and double solvent methods, and the latter comprises some new techniques such as the self-sacrificing template technique. Herein, we also reviewed their applications in hydrogen storage, ammonia adsorption, acidic gas adsorption, catalytic processes, and energy storage.

A new class of chiral semiconductors: chiral-organic-molecule-incorporating organic–inorganic hybrid perovskites

Abstract: An organic–inorganic hybrid perovskite incorporating chiral organic molecules is demonstrated as a new class of chiral semiconductors Chiral perovskites exhibit oppositely-signed circular dichroism (CD) according to the S- and R-configurations of chiral organics The CD signals can be also varied by changing the crystalline orientation and thickness of the chiral perovskite films

A multifunctional skin-like sensor based on a 3D printed thermo-responsive hydrogel

Abstract: An effective and general strategy is developed to prepare a multifunctional and mechanically compliant skin-like sensor by incorporating a 3D printed thermo-responsive hydrogel into a capacitor circuit. The prepared intelligent skin shows a sensitive and stable capacitance–temperature response, and also exhibits very high pressure sensitivity within 1 kPa, allowing it to sense body temperature, gentle finger touches and finger bending motion. This work not only demonstrates that stimuli-responsive hydrogels are promising candidates for artificially intelligent skins, but might also enrich the design of skin-like sensors for future artificial intelligence, wearable devices and human/machine interaction applications.

Flexible quasi-solid-state planar micro-supercapacitor based on cellular graphene films

Abstract: A quasi-solid-state micro-supercapacitor with cellular graphene film as the active material and polyvinyl alcohol/H3PO4 as the gel electrolyte is demonstrated as a new type of flexible energy storage device. The 3D porous graphene films not only serve as high performance supercapacitor electrodes, but also provide an abundant ion reservoir for the gel electrolyte. The quasi-solid-state micro-supercapacitor exhibits excellent electrochemical performance.

Programming 2D/3D shape-shifting with hobbyist 3D printers

Abstract: Materials and devices with advanced functionalities often need to combine complex 3D shapes with functionality-inducing surface features. Precisely controlled bio-nanopatterns, printed electronic components, and sensors/actuators are all examples of such surface features. However, the vast majority of the refined technologies that are currently available for creating functional surface features work only on flat surfaces. Here we present initially flat constructs that upon triggering by high temperatures change their shape to a pre-programmed 3D shape, thereby enabling the combination of surface-related functionalities with complex 3D shapes. A number of shape-shifting materials have been proposed during the last few years based on various types of advanced technologies. The proposed techniques often require multiple fabrication steps and special materials, while being limited in terms of the 3D shapes they could achieve. The approach presented here is a single-step printing process that requires only a hobbyist 3D printer and inexpensive off-the-shelf materials. It also lends itself to a host of design strategies based on self-folding origami, instability-driven pop-up, and ‘sequential’ shape-shifting to unprecedentedly expand the space of achievable 3D shapes. This combination of simplicity and versatility is a key to widespread applications.

Ultrasensitive and stretchable resistive strain sensors designed for wearable electronics

Abstract: Advanced wearable sensors for human motion detection are receiving growing attention and have great potential for future electronics. Herein, we demonstrate microcrack-assisted strain sensors using silver nanowires@patterned polydimethylsiloxane. Through designed percolating network microstructures, the strain sensors have significant inherent advantages, including simple fabrication processes and ultrahigh sensitivity far surpassing other stretchable sensing devices. Noteworthily, the strain sensors possess a tremendous gauge factor (GF) of 150 000 within a large stretchability of 60% strain range. The sensing mechanism depends on the change in electrical resistance, which is dramatically affected by a percolating-microcrack surface microstructure in the case of strain concentration of mechanical deformation. The superior sensing performance in conjunction with an appealing stretchability, reversibility, low creep and ultrahigh stability enables the strain sensors to act as wearable monitors and electronic skins for diverse applications, including but not limited to full-range detection of human body motions, as well as visual control of a light-emitting diode indicator, etc.

A highly sensitive graphene woven fabric strain sensor for wearable wireless musical instruments

Abstract: Highly flexible and sensitive strain sensors are essential components of wearable electronic devices. Herein, we present a novel graphene woven fabric (GWF)/polydimethylsiloxane (PDMS) composite as a highly flexible, sensitive strain sensor capable of detecting feeble human motions with an extremely high piezoresistive gauge factor of 223 at a strain of 3% and excellent durability. A wireless wearable musical instrument prototype made of the composite sensor demonstrates conversion of human motions to music of different instruments and sounds.

Simply realizing “water diode” Janus membranes for multifunctional smart applications

Abstract: A facile strategy for the preparation of multifunctional Janus membranes (JMs) was proposed, and excellent controllability of the multifunctional JMs was demonstrated in water collection, lossless transportation, decontamination, and on-off control. This novel strategy will accelerate the evolution of JMs from a scientific concept to usable materials for the “real” world.

Engineering gold-based radiosensitizers for cancer radiotherapy

Abstract: Radiotherapy remains a major modality in cancer therapy. The main goal of radiotherapy is to shrink tumors and kill cancer cells by using high-energy radiation, such as X-rays and γ-rays. Despite the effectiveness of radiotherapy in treating cancer in many possible ways, harmful damage caused by such radiation to the surrounding healthy/normal cells is often unavoidable. Therefore, it would be desirable to strike the right balance between tumor eradication and minimizing the possible side effects. To address this challenge, a magic bullet is the “radiosensitizer”, which can make cancer cells more sensitive to radiation by increasing the local treatment efficiency using a relatively low and safe radiation dose. This review article focuses on the recent progress in the area of radiosensitizers, especially gold-based materials. It begins with the key factors associated with radio-biological interactions along with the possible biological effects upon irradiation and from which the idea of radiosensitizers is derived. The prospect of gold-based materials as radiosensitizers is summarized through the mechanistic elucidation of the interaction of radiation with gold. Following that, some of the key design strategies for generating ideal gold-based radiosensitizers are highlighted. Examples of gold-based materials derived from these strategies, such as gold nanoparticles and nanoclusters, and their applications in radiotherapy are presented and discussed. The final part of this review article focuses on the avenues for future research on engineering gold-based nanomaterials for cancer radiotherapy.

Graphene/graphitic carbon nitride hybrids for catalysis

Abstract: Benefiting from the large specific surface area, outstanding electronic, optical, thermal and mechanical properties of graphene, as well as the exceptional electronic band structure and good physicochemical stability of graphitic carbon nitride (g-C3N4), graphene/g-C3N4 hybrids present great potential in electrochemical and photochemical catalysis. In this review, we summarize recent research advances in synthesizing graphene/g-C3N4 hybrid-based catalysts, and their applications in energy conversion, environmental decontamination, and other fields. The current limitations and some future trends of graphene/g-C3N4 hybrid-based nanomaterials as advanced catalysts are also discussed.

Assembly of hollow mesoporous nanoarchitectures composed of ultrafine Mo2C nanoparticles on N-doped carbon nanosheets for efficient electrocatalytic reduction of oxygen

Abstract: A simple method is developed to assemble Mo2C nanocrystals on the surfaces of hollow, highly conductive mesoporous nanoparticles. Diblock copolymer (PS-b-PEO) micelles are used as templates to assist in the fast complexation of molybdate (MoO42−) and polydopamine (PDA) precursors to make hollow precursor MoO42−/PDA/PS-b-PEO particles. Then these particles are carbonized to generate mesoporous N-doped carbon nanosheets riddled with ultrafine molybdenum carbide (Mo2C) nanoparticles (MMo2C/NCS). An N-doped carbon matrix serves as an electron conductor and helps to prevent the aggregation of the Mo2C nanoparticles. The Mo2C nanoparticles in turn enhance the catalytic performance for the oxygen reduction reaction (ORR). The unique mesoporous 2D nanosheet and its derived 3D hollow structure expose numerous active catalytic sites while enabling free diffusion of the electrolyte and mass transfer. Based on these properties, MMo2C/NCS show enhanced catalytic activity for the ORR.

Two-dimensional black phosphorus nanosheets for theranostic nanomedicine

Abstract: The fast progress of theranostic nanomedicine has catalyzed the generation of diverse inorganic nanosystems with intrinsic multifunctionalities for versatile biomedical applications. However, these inorganic biomaterials suffer from the critical issue of low biodegradation rates and subsequently long-term accumulation-induced biosafety risk. Furthermore, the components of some inorganic nanosystems are not the necessary elements/components of the body, unavoidably causing immune response and inducing the toxic potential. The emergence of ultrathin two-dimensional black phosphorus (B.P.) nanosheets as a robust platform promises the clinical translation and biomedical applications of inorganic nanosystems based on their intriguing nature of easy biodegradation and single phosphorus composition, as necessarily required in vivo. This review summarizes and discusses the very recent developments and paradigms of ultrathin B.P. nanosheets in versatile biomedical applications, ranging from design/fabrication strategies, theranostic nanomedicine (PDT/PTT/chemotherapy, synergistic therapy and fluorescence/photoacoustic-based bio-imaging) to biosensing applications. The unique biological behavior and toxicity issue of these B.P. nanosheets are also discussed to guarantee their safe clinical translation. It is highly expected that the elaborately designed/engineered B.P. nanosheets will emerge as one of the most representative biodegradable inorganic nanosystems for versatile and immense biomedical applications to benefit the health of human beings.

Improving photoanodes to obtain highly efficient dye-sensitized solar cells: a brief review

Abstract: Dye-sensitized solar cells (DSSCs) feature low cost, stability, and environment friendliness and are thus a promising substitute for traditional silicon solar cells. DSSCs have received intensive research attention and have been rapidly developing in the last two decades. The efficiency of DSSCs should be increased to promote their commercialization and large-scale application. This brief review summarizes the major progress in advanced nano/micromaterials to improve photoanodes and enhance the conversion efficiencies of DSSCs. Commonly used methods to improve photoanodes include semiconductor film nanoarchitecture, light-scattering material application, compositing, doping, interfacial engineering, and TiCl4 post-treatment. This review provides insights into DSSC improvement and development of other photovoltaics, such as perovskite solar cells and photoelectrochemical cells.

Heteroatom-doped graphene as electrocatalysts for air cathodes

Abstract: Fuel cells and metal–air batteries are promising energy storage and conversion devices owing to their ultrahigh theoretical energy density However, at present, it is still challenging to achieve the super-high energy density in practical applications due to the sluggish electrochemical reaction kinetics on air cathodes, which makes it urgent to exploit high-efficiency electrocatalysts In the past decade, heteroatom-doped graphene (H-G) materials have drawn extensive attention due to their good catalytic activity, large specific surface area and high electrical conductivity In this review, we focus on the summary of the latest advances regarding H-G electrocatalysts for air cathode-containing devices, including the synthetic methods of H-G materials and their applications to fuel cells, zinc–air batteries and lithium–air batteries The working principles and catalytic reaction mechanisms are discussed in detail Finally, the challenges and perspectives are presented to offer a guideline for the exploration of excellent H-G-based electrocatalysts

A unified understanding of charge transport in organic semiconductors: the importance of attenuated delocalization for the carriers

Abstract: The variety of charge transport theories for organic semiconductors (OSCs) raises the question of which models should be selected for each case, and there is a lack of generalized understanding regarding various OSCs over the full range of crystallinity from single crystal to amorphous. Here, we report that the generalized Einstein relation (GER) can unify various theoretical models and predict charge transport in OSCs with various crystallinities, by altering the variance of the density of states and the delocalization degree in a Gaussian-distributed density of states. The GER also provides a good fitting to much of the experimental data of temperature- and gate-voltage-dependent mobility for different OSCs in transistors. Consequently, disorders of charge transport in various OSCs can be directly compared in the same map, which reveals how energetic disorder and the delocalization degree determine charge transport in organic devices.

Advancements in rationally designed PGM-free fuel cell catalysts derived from metal–organic frameworks

Abstract: Over the past several years, metal–organic framework (MOF)-derived platinum group metal free (PGM-free) electrocatalysts have gained considerable attention due to their high efficiency and low cost as potential replacement for platinum in catalyzing oxygen reduction reaction (ORR). In this review, we summarize the recent advancements in design, synthesis and characterization of MOF-derived ORR catalysts and their performances in acidic and alkaline media. We also discuss the key challenges such as durability and activity enhancement critical in moving forward this emerging electrocatalyst science.

Hydrogels that listen to cells: a review of cell-responsive strategies in biomaterial design for tissue regeneration

Abstract: The past decade has seen a decided move from static and passive biomaterials to biodegradable, dynamic, and stimuli responsive materials in the laboratory and the clinic Recent advances towards the rational design of synthetic cell-responsive hydrogels—biomaterials that respond locally to cells or tissues without the input of an artificial stimulus—have provided new strategies and insights on the use of artificial environments for tissue engineering and regenerative medicine These materials can often approximate responsive functions of a cell's complex natural extracellular environment, and must respond to the small and specific stimuli provided within the vicinity of a cell or tissue In the current literature, there are three main cell-based stimuli that can be harnessed to create responsive hydrogels: (1) enzymes (2) mechanical force and (3) metabolites/small molecules Degradable bonds, dynamic covalent bonds, and non-covalent or supramolecular interactions are used to provide responsive architectures that enable features ranging from cell selective infiltration to control of stem-cell differentiation The growing ability to spatio-temporally control the behavior of cells and tissue with rationally designed responsive materials has the ability to allow control and autonomy to future generations of materials for tissue regeneration, in addition to providing understanding and mimicry of the dynamic and complex cellular niche

High performance aluminum–cerium alloys for high-temperature applications

Abstract: Light-weight high-temperature alloys are important to the transportation industry where weight, cost, and operating temperature are major factors in the design of energy efficient vehicles. Aluminum alloys fill this gap economically but lack high-temperature mechanical performance. Alloying aluminum with cerium creates a highly castable alloy, compatible with traditional aluminum alloy additions, that exhibits dramatically improved high-temperature performance. These compositions display a room temperature ultimate tensile strength of 400 MPa and yield strength of 320 MPa, with 80% mechanical property retention at 240 °C. A mechanism is identified that addresses the mechanical property stability of the Al-alloys to at least 300 °C and their microstructural stability to above 500 °C which may enable applications without the need for heat treatment. Finally, neutron diffraction under load provides insight into the unusual mechanisms driving the mechanical strength.

Vapor phase infiltration (VPI) for transforming polymers into organic–inorganic hybrid materials: a critical review of current progress and future challenges

Abstract: This review critically assesses the state-of-knowledge for vapor phase infiltration (VPI) processing science, an emerging gas phase processing scheme for producing organic–inorganic hybrid materials. In VPI, vapor phase metalorganic precursors are diffused into and subsequently reacted with organic polymers to transform them into organic–inorganic hybrid materials. While this processing technique originates from the atomic layer deposition (ALD) research community, and its processing conditions are similar to ALD, the fundamental phenomenological mechanisms of VPI and ALD are significantly different. In fact, the kinetics of VPI more closely parallel processes in gas membrane separations and solvent vapor annealing than ALD. This review clarifies the nomenclature and taxonomy of VPI within the greater family of chemical vapor phase processing techniques. The current understanding of VPI's atomic-scale processing phenomenology is reviewed, and a basic framework for understanding the processing kinetics is presented. Characterization methods for studying the processing dynamics and final material structure are summarized along with some current applications for the unique materials that are created. Most importantly, this article aims to unify the research field and identify several scientific challenges that must be overcome to advance this processing technology towards broad commercial acceptance.

Atomic layer deposition for nanomaterial synthesis and functionalization in energy technology

Abstract: Atomic layer deposition (ALD) has been receiving more and more research attention in the past few decades, ascribed to its unrivaled capabilities in controlling material growth with atomic precision, manipulating novel nanostructures, tuning material composition, offering multiple choices in terms of crystallinity, and producing conformal and uniform film coverage, as well as its suitability for thermally sensitive substrates. These unique characteristics have made ALD an irreplaceable tool and research approach for numerous applications. In this review, we summarize the recent advances of ALD in several important areas including rechargeable secondary batteries, fuel cells, solar cells, and optoelectronics. With this review, we expect to exhibit ALD's versatile potential in providing unique solutions to various technical challenges and also hope to further expand ALD's applications in emerging areas.