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Digital polymerase chain reaction (dPCR) technology has provided a new technique for molecular diagnostics, with superior advantages, such as higher sensitivity, precision, and specificity over quantitative real-time PCRs (qPCR). Eight companies have offered commercial dPCR instruments: Fluidigm Corporation, Bio-Rad, RainDance Technologies, Life Technologies, Qiagen, JN MedSys Clarity, Optolane, and Stilla Technologies Naica. This paper discusses the working principle of each offered dPCR device and compares the associated: technical aspects, usability, costs, and current applications of each dPCR device. Lastly, up-and-coming dPCR technologies are also presented, as anticipation of how the dPCR device landscape may likely morph in the next few years.

Pristine graphene supported ultrasmall, highly dispersed, and high-density Co–W–P nanoparticles were synthesized via phosphotungstic-acid-mediated self-assembly, showing superior HER catalytic performance.

High-density CdS nanosheets were vertically self-assembled on ZnO nanowire arrays, forming a photoanode with superior performance toward water splitting.

Highly conductive cocatalysts with great promotion effects are critical for the development of pristine graphene supported Pt-based catalysts for the methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). However, identification of these cocatalysts and controlled fabrication of Pt/cocatalyst/graphene hybrids with superior catalytic performance present great challenges. For the first time, pristine graphene supported N-rich carbon (NC) has been controllably fabricated via ionic-liquid-based in situ self-assembly for in situ growth of small and uniformly dispersed Pt NP chains to improve the MOR catalytic activity. It is discovered that the NC serves simultaneously as a linker to facilitate in situ nucleation of Pt, a stabilizer to restrict its growth and aggregation, and a structure-directing agent to induce the formation of Pt NP chains. The obtained nanohybrid shows a much higher forward peak current density than commercial Pt/C and most reported noncovalently functionalized carbon (NFC) supported Pt catalysts, a lower onset potential than almost all commercial Pt/C and NFC supported Pt, and greatly enhanced durability compared to graphene supported Pt NPs and commercial Pt/C. The superior catalytic performance is ascribed to the uniformly dispersed, small-diameter, and short Pt NP chains supported on highly conductive G@NC providing high ECSA and improved CO tolerance and the NC with high content of graphitic N greatly enhancing the intrinsic activity and CO tolerance of Pt and offering numerous binding sites for robustly attaching Pt. This work not only identifies and controllably fabricates a novel cocatalyst to significantly promote the catalytic activity of pristine graphene supported Pt but provides a facile and economical strategy for the controlled synthesis of high-performance integrated catalysts for the MOR in DMFCs.

The development of cost-effective and high-performance catalysts for the production of hydrogen via electrocatalytic water splitting is crucial for meeting the increasing energy demand and expanding the hydrogen economy. In this study, a series of metal-free carbon nanotube (CNT) catalysts were designed and in situ functionalized by imidazolium ionic liquids (ILs) for enhanced electrocatalytic hydrogen evolution reaction (HER). The theoretical calculations and experimental results reveal that the functionalization of CNTs with imidazolium ILs facilitated the electron transfer process and exhibited superior hydrogen adsorption, thereby enhancing the performance of the HER. In particular, CNT-IM-Cl displays excellent electrocatalytic activity and shows a low onset overpotential and Tafel slope of 80 mV and 38 mV dec-1, respectively. This study highlights the significant potential of IL in situ functionalized metal-free CNTs for the electrocatalytic HER and provides insight into the structure design of highly efficient electrocatalysts.

Metal–organic complex (MOC) multilayers are, for the first time, conformally constructed on Ni foam (NF) via a three-component sequential layer-by-layer (LbL) self-assembly approach and converted t...

Controlled assembly of small and highly dispersed earth-abundant transition metal-based oxygen evolution reaction (OER) catalysts on pristine graphene could greatly boost the OER efficiency while s...

Efficient and stable water-splitting electrocatalysts play a key role to obtain green and clean hydrogen energy. However, only a few kinds of materials display an intrinsically good performance towards water splitting. It is significant but challengeable to effectively improve the catalytic activity of inert or less active catalysts for water splitting. Herein, we present a structural/electronic modulation strategy to convert inert AlOOH nanorods into catalytic nanosheets for oxygen evolution reaction (OER) via ball milling, plasma etching and Co doping. Compared to inert AlOOH, the modulated AlOOH delivers much better OER performance with a low overpotential of 400 mV at 10 mA cm

Morphological control of noble-metal-based nanocrystals has attracted enormous attention because their catalytic behaviors can be optimized well by adjusting the size and shape. Herein, the controllable synthesis of web-footed PdCu nanosheets via a facile surfactant-free method is reported. It is discovered that the Cu(II) precursor in this synthetic system displays a critical role in growing branches along the lateral of nanosheets. This work demonstrates a Pd-based alloy nanoarchitecture for efficient and stable electrocatalysis of both ethanal and formic acid oxidation reactions.

Pd-based catalysts with maximized exposure of active sites, ultrafast electron transport, and cocatalyst-promoted intrinsic activity are highly desirable for the formic acid oxidation reaction (FAOR), but their fabrication presents a formidable challenge. For the first time, dynamic self-assembly of adenine has been utilized for growth of ultrasmall, highly dispersed, and clean Pd NPs on pristine graphene. The obtained nanohybrid shows remarkably enhanced FAOR catalytic activity and durability compared to Pd NPs directly grown on pristine graphene and commercial Pd/C. The activity is also among the highest for Pd-based catalysts. The excellent catalytic performance is due to well-dispersed, ultrasmall, and clean Pd NPs intimately grown on pristine graphene offering numerous electrochemically accessible active sites and preserving high intrinsic catalytic activity of Pd, great cocatalytic effect of pristine graphene enhancing CO tolerance and intrinsic activity of Pd, and robust attachment of Pd with high CO tolerance on graphene providing high durability. This study develops a facile, mild, and economical strategy to create pristine graphene supported clean Pd NPs with outstanding FAOR catalytic performance, and also sheds light on the mechanism of dynamically self-assembled adenine-mediated synthesis, which is extendable to fabricate other nanohybrids.

Batteries coupled to photovoltaic (PV) modules have been identified as a viable power source for independent “internet of things” portable electronic devices and to reduce the grid load during peak times. However, the poor matching of these systems can adversely affect the power conversion efficiency, safety, and cost due to increased charge control strategies and supporting load management equipment. In this work, we significantly improve the rate performance of the battery electrodes by asphalt-derived carbon coating, and strategically couple high-efficiency n-i-p type perovskite solar cells with either aqueous lithium or sodium (Li/Na)-ion batteries, for the first time, to create a low-cost and high-performance photovoltaic battery system. Both photovoltaic battery systems demonstrate stable cycling performance for at least 30 cycles. We also demonstrate a high energy-conversion and storage efficiency of about 9.3% at a high discharge rate of 2 C and show that this is significantly superior than previously integrated photovoltaic battery systems. We suggest that the enhanced power and efficient energy transfer between the perovskite solar cells and aqueous Li/Na-ion batteries make this system attractive for a wide range of energy needs.

Hydrogen evolution catalysts with effectively integrated structures at different length scales are promising to remarkably boost the efficiency of the hydrogen evolution reaction (HER), but their f...

For the first time, graphene-supported N-doped carbon (G@NC) with a high degree of N doping was synthesized by in situ self-assembly of a glucaminium-based ionic liquid on pristine graphene under hydrothermal conditions. This 2D, metal-free nanohybrid exhibited much higher catalytic activity than most reported metal-free catalysts for the oxygen evolution reaction (OER) and even state-of-the-art Ir- and Ru-based catalysts because the high content of graphitic N greatly increased the number of OER-active sites, the pristine graphene significantly promoted the OER activity of the C sites adjacent to the graphitic N atoms, and N-doped graphitic carbon remarkably enhanced the charge-transfer rate. This work not only creates a facile and economical approach to controllably fabricate pristine-graphene-supported carbon with a high N-doping level for the development of highly efficient metal-free OER catalysts but also provides insight into the mechanisms for both the in situ self-assembly and the high OER catalytic activity of G@NC.

Oxygen evolution reaction (OER) represents a major kinetic bottleneck for water splitting. Three-dimensional (3-D) Ni foam (NF) supported pristine few-layer graphene was utilized as an oxygen evolution electrode, showing an overpotential of 382 mV to achieve 10 mA cm−2 and a Tafel slope of 44.9 mV dec−1, both of which are lower than those of pristine NF and graphene and among the lowest reported for carbon and even transition metal-based catalysts measured under the same conditions, and much higher steady-state current density and much less reduction of current density after CV cycling compared to NF and graphene, with negligible current loss after 10 h chronoamperometry and 350 CV cycles. Its high catalytic performance is possibly due to the Ni-promoted OH− adsorption on and uniform dispersion and charge redistribution of the robustly attached graphene. This study not only provides a novel strategy to significantly enhance the OER activity of pristine graphene and creates a high-performance 3-D and binder-free oxygen evolution electrode, but offers scientific insight into the promotion effect of metal supports on the OER activity of pristine graphene.

The development of cost-effective and high-performance catalysts for the production of hydrogen via electrocatalytic water splitting is crucial for meeting the increasing energy demand and expanding the hydrogen economy. In this study, a series of metal-free carbon nanotube (CNT) catalysts were designed and in situ functionalized by imidazolium ionic liquids (ILs) for enhanced electrocatalytic hydrogen evolution reaction (HER). The theoretical calculations and experimental results reveal that the functionalization of CNTs with imidazolium ILs facilitated the electron transfer process and exhibited superior hydrogen adsorption, thereby enhancing the performance of the HER. In particular, CNT-IM-Cl displays excellent electrocatalytic activity and shows a low onset overpotential and Tafel slope of 80 mV and 38 mV dec-1, respectively. This study highlights the significant potential of IL in situ functionalized metal-free CNTs for the electrocatalytic HER and provides insight into the structure design of highly efficient electrocatalysts.

Poor room-temperature ionic conductivity and lithium dendrite formation are the main issues of solid electrolytes. In this work, rod-shaped alumina incorporation and graphite coating were simultaneously applied to poly (propylene carbonate) (PPC)-based polymer solid electrolytes (Wang et al., 2018). The obtained alumina modified solid electrolyte membrane (Al-SE) achieves a high ionic conductivity of 3.48 × 10−4 S/cm at room temperature with a wide electrochemical window of 4.6 V. The assembled NCM622/Al-SE/Li solid-state battery exhibits initial discharge capacities of 198.2 mAh/g and 177.5 mAh/g at the current density of 0.1 C and 0.5 C, with the remaining capacities of 165.8 mAh/g and 161.3 mAh/g after 100 cycles respectively. The rod-shaped structure of Al2O3 provides fast transport channels for lithium ions and its Lewis acidity promotes the dissociation of lithium salts and release of free lithium ions. The lithiophilic Al2O3 and Graphite form intimate contact with metallic Li and create fast Li+ conductive layers of Li-Al-O layer and LiC6 layer, thus facilitating the uniform deposition of Li and inhibiting Li dendrite formation during long-term cycling. This kind of composite Al-SE is expected to provide a promising alternative for practical application in solid electrolytes.

Photoelectrochemical (PEC) water splitting represents a promising strategy to convert solar energy into chemical energy in the form of hydrogen, but its performance is severely limited by the sluggish water oxidation reaction. Herein, for the first time, we report the direct assembly of an ultrathin, uniform, and dense layer of Co3O4 on wormlike nanostructured hematite (WN-α-Fe2O3) to form a large-area and high-density WN-α-Fe2O3@Co3O4 core-shell nanoarray via in situ hydrothermal growth followed by calcination, in which the electrostatic force between WN-α-Fe2O3 and the reactants, pH- and temperature-controlled structures of WN-α-Fe2O3, and ultralow nucleation rate of Co3O4 precursors all play critical roles. The obtained heteronanostructure array shows a photocurrent density of 3.48 mA cm-2, which is 4.05 times higher than that of pristine WN-α-Fe2O3 (0.86 mA cm-2), an onset potential of ∼0.62 V, 60 mV lower than that of α-Fe2O3 (∼0.68 V), and a photoconversion efficiency of 0.55%, 3.93 times higher than that of WN-α-Fe2O3 (0.14%). This is among the highest performances reported for Fe2O3-based photoanodes for water splitting. It is discovered that the Co3O4 shells can significantly enhance the charge separation, accelerate the charge transport and transfer, and reduce the charge transfer resistance from the photoelectrode to the electrolyte for a fast water oxidation reaction, thereby greatly promoting the PEC water oxidation performance of pristine WN-α-Fe2O3. This work not only creates a novel low-cost and Earth-abundant WN-α-Fe2O3@Co3O4 photoelectrode with superior PEC water oxidation performance and provides scientific insights into the enhancement mechanism, but also offers a general strategy for the in situ growth of water oxidation catalysts on various photoelectrodes with 3-D complex geometries for PEC water splitting.

Small-sized nanocrystals uniformly distributed on suitable supports are promising as active electrocatalysts due to their unique electronic structure and high accessible surface area. Herein, we report the synthesis of graphene supported PdCu nanoclusters with a uniform size of 2.3 nm via a facile one-pot solvothermal method. This nanohybrid exhibits much higher inherent catalytic activity and stability for formic acid oxidation in comparison to graphene supported Pd clusters and commercial Pd/C. The PdCu nanoclusters can maintain their original size and dispersity on graphene even after 200 CV cycles. This work offers an efficient low Pd-loading catalyst for formic acid oxidation, and the synthetic approach is of significance to preparing uniform metal-based clusters decorated on supports with superior catalytic properties for fuel cells and sensors.

Poor interface stability is a crucial problem hindering the electrochemical performance of solid-state lithium batteries. In this work, a novel approach for interface stability was proposed to integrate the cathode/solid electrolyte by forming an electrolyte buffer layer on the rough surface of the cathode and coating a layer of graphite on the side of the electrolyte facing the lithium anode. This hybrid structure significantly improves the integration and the interface stability of the electrode/electrolyte. The interfacial resistance was dramatically reduced, the stability of the plating/stripping of Li metal was enhanced, and the growth of lithium dendrites was also inhibited due to the formation of the LiC6 transition layer. The obtained solid-state lithium battery shows enhanced rate performance at room temperature from 0.5 to 4 C and stable cycling performance at 1 C with a retention capacity of 100 mAh g-1 after 200 cycles. This integrated electrode/electrolyte design approach is expected to be widely used to improve interfacial stability and room-temperature electrochemical performance of solid-state batteries.

Developing highly active, earth-abundant, and durable electrocatalysts is desired but challenging for oxygen evolution reaction (OER). In this work, we design an electrocatalyst of the edge-rich nickel sulfide arrays on the nickel foam (Ni3S2 NSs-NF) by a facile yet efficient wet-chemical method. Benefiting from the three-dimensional nanostructure with numerous active edges, the prepared Ni3S2 NSs-NF exhibits superior OER performance in alkaline conditions. An in-depth study reveals that the real active sites toward OER are the in situ formed heterogenous Ni3S2-NiOOH. Density functional theory (DFT) calculations indicate the density of state (DOS) of the Ni3S2-NiOOH heterojunction near the Fermi level is enhanced, contributing to higher electronic conductivity. As a result, the Ni3S2 NSs-NF with abundant Ni3S2-NiOOH heterojunctions exhibits an efficient electrochemical activity toward OER in alkaline conditions. The Ni3S2 NSs-NF electrode shows an overpotential of 244 mV at 10 mA cm−2 with a Tafel slope of 75 mV dec−1 and possesses ultrastable performance even at 100 mA cm−2.

3D ZIF-67-particles-impregnated cellulose-nanofiber nanosheets with oriented macropores are synthesized via directional-freezing-assisted in situ self-assembly, and converted to 3D CoP-nanoparticle (NP)-embedded hierarchical, but macropores-oriented, N-doped carbon nanosheets via calcination and phosphidation. The obtained nanoarchitecture delivers overpotentials at 10 and 50 mA cm

The in situ growth of Pd nanoflowers on pristine graphene is achieved using phosphomolybdic acid (HPMo) to mediate self-assembly. The HPMo serves simultaneously as a linker, stabilizer, and structure-directing agent, and the nanoflowers are formed by kinetically controlled growth. When the resulting material, Pd nanoflowers on HPMo-modified graphene (HPMo-G) support, is used to catalyze the formic acid oxidation reaction (FAOR), much higher catalytic activity and durability are found than with HPMo-G supported Pd nanospheres, graphene supported Pd nanoparticles, and commercial Pd/C catalysts. The catalytic activity for Pd nanoflowers on HPMo-G is also among the highest reported for Pd-based catalysts. The superior electrocatalytic performance is attributed to the unique nanoflower shape, a promotion by the HPMo mediator, and the excellent support properties of pristine graphene. The use of HPMo to mediate self-assembly of metals on graphene can be extended to fabricate other hybrid nanostructures promisin...

Clean and uniform Pt3Au clusters decorated on graphene (Pt3Au@PDDA-G) with an average size as small as 2.1nm were successfully synthesized, offering higher catalytic activity and stability toward ethanol oxidation than that of Pt3Au@G and commercial Pt/C, respectively. The catalytic enhancement mechanism of Pt3Au@PDDA-G was proposed and discussed, and this work demonstrated that the uniformly distributed Pt3Au clusters could strongly suppress Ostwald ripening to retain their original crystals size and morphology for highly catalytic properties. Keywords: Pt3Au, Clusters, Catalyst, Ethanol oxidation, Ostwald ripening, Fuel cells

Layer-by-layer (LbL) assembly is a nanoscale technique with great versatility, simplicity and molecular-level processing of various nanoscopic materials. Weak polyelectrolytes have been used as major building blocks for LbL assembly providing a fundamental and versatile tool to study the underlying mechanisms and practical applications of LbL assembly due to its pH-responsive charge density and molecular conformation. Because of high-density uncompensated charges and high-chain mobility, weak polyelectrolyte exponential multilayer growth is considered one of the fastest developing areas for organized molecular films. In this article, we systematically review the current status and developments of weak polyelectrolyte-based multilayers including all-weak-polyelectrolyte multilayers, weak polyelectrolytes/other components (e.g. strong polyelectrolytes, neutral polymers, and nanoparticles) multilayers, and exponentially grown weak polyelectrolyte multilayers. Several key aspects of weak polyelectrolytes are highlighted including the pH-controllable properties, the responsiveness to environmental pH, and synergetic functions obtained from weak polyelectrolyte/other component multilayers. Throughout this review, useful applications of weak polyelectrolyte-based multilayers in drug delivery, tunable biointerfaces, nanoreactors for synthesis of nanostructures, solid state electrolytes, membrane separation, and sensors are highlighted, and promising future directions in the area of weak polyelectrolyte-based multilayer assembly such as fabrication of multi-responsive materials, adoption of unique building blocks, investigation of internal molecular-level structure and mechanism of exponentially grown multilayers, and exploration of novel biomedical and energy applications are proposed.

Capacitive devices have drawn a beautiful application scene in electronic device systems ranging from touch sensors, energy storages and multifunction transistors, but serving as memristive term is still blank. Sweet potato peel (SPP) as function layer was employed to develop the memristive device with Ag/SPP/F-doped SnO2 (FTO) structure. A current-voltage (I-V) hysteresis, which is characterized by a typical capacitive behavior, is impressively observed in the developed device. Nonvolatile data storage is feasible using the non-zero-crossing I-V hysteresis because the resistance states can be well maintained. Charge transfer at the Ag/SPP and SPP/FTO interfaces, and the interplay between Ag+ ions and charges are responsible for this non-zero-crossing I-V hysteresis behaviors. This work possibly gives an insight into the data storage in terms of a new conception electronic device based on environment-friendly material.

Magnesium doping is successfully utilized to enhance the electrochemical performance of Na2FeP2O7 for sodium-ion batteries (SIBs). A series of morphological and electrochemical tests indicate that Mg doping does not affect the structures of the host phase and the abundant defects in carbon coating are beneficial for electronic conductivity. A new peak at ~2.70 V during the first few cycles in CV curves is observed, which is related to the increase of specific capacity during the lifespan test. DFT calculation results reveal the enhanced electronic conductivity in Mg doped Na2FeP2O7, which is consistent with experimental observations. The Na2FeP2O7 with an appropriate Mg doped of 5% exhibits an initial reversible capacity of 90 mAh g−1 at 0.1 C without an obvious decline after 2000 cycles at 9 C. The specific capacity of Mg doped Na2FeP2O7 does not decrease fatally even the amount of Mg doped comes to 20%. The Coulombic efficiency is very high, close to 100% in all samples. The excellent electrochemical performance of Mg doped Na2FeP2O7 presents great potential as cathodes for advanced SIBs.

Three-dimensional (3-D) composite oxygen evolution electrodes with synergistic effects are promising to significantly boost the efficiency of the oxygen evolution reaction (OER). However, their fabrication presents great challenges. Herein, for the first time we show that layer-by-layer (LbL) self-assembly on 3-D substrates can be employed to controllably fabricate 3-D composite electrodes. Ni foam (NF) supported poly(ethyleneimine) (PEI)/reduced graphene oxide (RGO) multilayers fabricated via this approach have tunable catalytic properties. The optimum one achieves the current density of 10 mA cm−2 at an overpotential of 322 mV, which is lower than those of most reported transition metal-based OER catalysts and non-metal ones as well as those of state-of-the-art Ir/C, Ru/C, IrO2/C, and RuO2 measured under the same conditions (0.1 M KOH). It shows a Tafel slope of 78 mV dec−1, which is among the lowest reported for transition metal-based OER catalysts and non-metal ones and comparable to or even lower than that of state-of-the-art Ir and Ru-based ones measured in 0.1 M KOH. In addition, this electrode exhibits a potential increase from 0.55 V to 0.58 V vs. SCE after 18.8 h of chronopotentiometry testing at 10 mA cm−2 and retains 85.8% of the current density at 1.0 V vs. SCE after 350 CV cycles, revealing its good stability. The high catalytic performance could be attributed to in situ formed Ni(OH)2 with RGO-promoted activity, high-density C[double bond, length as m-dash]O rich edge-exposed RGO nanosheets, and the covalently crosslinked multilayer structure of chemically stable RGO nanosheets. All of these properties arise from synergistic interactions between NF, PEI, and RGO. This work offers a facile, mild, controllable, and economical strategy to synergistically assemble conventional poor OER catalysts for low-cost, highly active, and durable 3-D OER electrodes. It also provides scientific insight into the mechanism for the superior and tunable OER catalytic activity, which is critical for further improving the OER catalytic performance.

Highly active, durable, and low-cost hydrogen evolution reaction (HER) catalysts are critical for large-scale energy storage in the form of hydrogen through water splitting but their fabrication presents great challenges. Herein we report the synthesis of a novel 3D hierarchical nanoporous CoP nanoflowers/pristine graphene interconnected network structure via diethylenetriamine (DETA)-mediated self-assembly, in which DETA promoted the uniform dispersion of graphene and the nucleation of the CoP precursor on graphene, the seed aggregation facilitated the formation of nanoflowers and a 3D network, and the gas release during the low-temperature phosphidation produced nanopores inside the nanoflowers. This nanoarchitecture shows an onset potential of −0.014 V, an overpotential of 98.1 mV to achieve 10 mA cm−2, a Tafel slope of 40.9 mV dec−1, and an exchange current density of 0.119 mA cm−2. The onset overpotential, overpotential to achieve 10 mA cm−2, and Tafel slope are all among the lowest reported for non-noble metal hydrogen evolution reaction (HER) catalysts, and the exchange current density also compares favorably to those of most reported HER catalysts. In addition, the catalyst exhibits excellent durability with negligible loss in current density after 2000 cyclic voltammetry (CV) cycles (+0.01 to −0.17 V vs. the RHE, at a scan rate of 100 mV s−1) or 23.5 h of chronoamperometric measurement at an overpotential of 98.1 mV, and a high faradaic efficiency of close to 100%. This work not only creates a high-performance and inexpensive HER electrocatalyst by utilizing the great advantages of 3D hierarchically nanostructured networks, but also develops a facile and economical strategy for the self-assembly of hierarchical nanostructures and offers scientific insight into its mechanism.

The sluggish oxygen evolution reaction (OER) represents a major kinetic bottleneck in water splitting. Herein we report the synthesis of a novel Ni foam (NF) supported 3-D vertically aligned and interconnected layered CoO nanosheet array with controlled density, layer thickness, and interlayer spacing, and the conformal self-assembly of graphene on this nanosheet array. The obtained CoO layered nanosheet/graphene hybrid nanoarray was directly used as an OER electrode, showing a current density of 10 mA cm −2 at an overpotential of 330 mV and a Tafel slope of 79 mV dec −1 , both of which are much lower than pristine NF and the nanosheet array without graphene, and are among the lowest reported for Co-based OER catalysts and transition metal oxide-based ones measured under the same conditions. In addition, it can retain 92.4% of the current density after 66 h of chronoamperometry testing at a potential of 1.0 V vs. SCE, and 94.3% of the current density at 1.0 V vs. SCE after 200 cyclic voltammetry cycles (0–1.0 V vs. SCE). The excellent catalytic activity and stability toward OER are ascribed to the 3-D NF supported robustly grown networked layered nanosheet array structure and the synergistic effects between CoO layered nanosheets and graphene.

Phototoelectrochemical (PEC) water splitting represents a highly promising strategy to convert solar energy to chemical energy in the form of hydrogen, but its performance is severely limited by the water oxidation reaction. We conformally grew an ultrathin and continuous coating of Cu2O on TiO2 nanowire array (NWA) to form a truly core-shell TiO2@Cu2O NWA via a new facile, economical, and scalable polymer-mediated self-assembly approach, in which the polymer serves as a stabilizer, reductant, and linker simultaneously. This heteronanostructure was subsequently directly used as a photoanode for PEC water splitting, showing a photocurrent density of 4.66 mA cm(-2) at 1.23 V vs RHE in 0.5 M Na2SO4 solution and a maximum photoconversion efficiency of 0.71%, both of which are the highest reported for TiO2-based photoanodes measured under the same conditions (neutral conditions and without any sacrificial agent). The superior PEC performance of the TiO2@Cu2O NWA toward water oxidation is primarily due to much enhanced visible light collection and charge separation for high charge carrier density as well as greatly facilitated charge transfer and transport. This work not only offers a novel TiO2@Cu2O core-shell NWA photoanode for highly efficient PEC water oxidation and investigate its enhancement mechanism but also provides scientific insights into the mechanism of the polymer-mediated self-assembly, which can be further extended to fabricate various other core-shell nanoarchitectures for broad applications.

Carbon materials are the commonly used catalyst supports for energy conversion and storage systems thanks to their high electronic conductivity and large specific surface area. Herein, hierarchical interconnected graphene oxide is synthesized using a facile thermally-induced expansion reduction approach, exhibiting a mainly direct pathway of four-electron transfer process toward oxygen reduction reaction. Compared to normal graphene oxide sheets, the hierarchical graphene oxide shows 38 mV more positive half-wave potential. It also shows remarkable methanol tolerance ability and better electrochemical stability than the commercial Pt/C. Its catalytic enhancement mechanism could be attributed to the architecture of interconnected hierarchical structure, which could offer appropriate distances for the bridge mode of oxygen adsorption. This work offers scientific insights on tailored graphene oxide nanostructures as an advanced electrocatalyst for fuel cells and beyond.

Noble metal-based nanosheets are demonstrated as promising electrodes for energy electrocatalysis due to their remarkable advantages such as large surface area to volume ratio and high utilization efficiency of noble metals. In this work, three-dimensional layered palladium tungsten nanosheet assemblies (L-PdW NAs) have been successfully synthesized using a facile carbon monoxide (CO) confinement strategy, exhibiting much higher catalytic activity and stability toward both ethanol oxidation reaction (EOR) and methanol oxidation reaction (MOR) compared to palladium nanosheets (Pd NSs) and commercial Pd/C (Com Pd/C). It is discovered that the tungsten hexacarbonyl (W(CO)6) in the synthetic system displays a decisive key in forming the layered nanosheet structure. The catalytic enhancement mechanism should result the synergetic effects between the introduced W and novel architecture of layered nanosheet assembles. This work offers a low Pd loading, highly active and stable anode catalyst for direct alcohol fuel cells, while highlighting the beauty of the architecture with introduced W to significantly enhance the catalytic activity.