Green growth path dependence momentum under the prism of COP26: the role of financial deepening, ICT development, and export diversification.

Financial deepening is important in resource allocation for more productive enterprises, leading to sustainable green growth. Moreover, rapid development in the digital economy and export diversification significantly affect green growth. From this perspective, our study explores the impact of financial deepening, ICT development, and export diversification on green growth in China's economies from 1996 to 2021. The study explores the linkage between financial deepening, ICT development, export diversification, and green growth by employing the nonlinear autoregressive distributed lag (NARDL) approach. The results obtained in the long run are as follows: positive shock in financial deepening brings positive change in green growth, whereas negative shock in financial deepening reduces green growth. In the long run, positive shock in ICT enhances green growth, but negative shock in ICT does not impact green growth. Moreover, positive shock in export diversification brings positive change in green growth, whereas negative shock in export diversification reports an insignificant impact on green growth. Based on findings, it is suggested that financial deepening, ICT development, and export diversification are conducive to sustainable green growth.

Dual-Mode Conversion of Photodetector and Neuromorphic Vision Sensor via Bias Voltage Regulation on a Single Device.

Simultaneous implementation of photodetector and neuromorphic vision sensor (NVS) on a single device faces a great challenge, due to the inherent speed discrepancy in their photoresponse characteristics. In this work, a trench-bridged GaN/Ga2 O3 /GaN back-to-back double heterojunction array device is fabricated to enable the advanced functionalities of both devices on a single device. Interestingly, the device shows fast photoresponse and persistent photoconductivity behavior at low and high voltages, respectively, through the modulation of oxygen vacancy ionization and de-ionization processes in Ga2 O3 . Consequently, the role of the optoelectronic device can be altered between the photodetector and NVS by simply adjusting the magnitude of bias voltage. As a photodetector, the device is able to realize fast optical imaging and optical communication functions. On the other hand, the device exhibits outstanding image sensing, image memory, and neuromorphic visual pre-processing as an NVS. The utilization of NVS for image pre-processing leads to a noticeable enhancement in both recognition accuracy and efficiency. The results presented in this work not only offer a new avenue to obtain complex functionality on a single optoelectronic device but also provide opportunities to implement advanced robotic vision systems and neuromorphic computing.

Energy technology innovation through the lens of the financial deepening: Financial institutions and markets perspective.

This paper examines the impact of financial deepening on energy technology green innovation over the period 1996 to 2020. Utilizing the nonlinear QARDL technique, we assess the asymmetric short and long-term impacts across various quantiles. The research employs two measures of financial deepening, namely financial institution deepening (FID) and financial market deepening (FMD). The findings reveal that a positive change in the FID causes energy green innovation to rise, while a negative change in the FID causes energy green innovation to fall in the long run at most quantiles. Further, we find that the rise in the FMD help improves energy green innovation; however, the fall in the FMD does not significantly impact energy green innovation at all quantiles. Based on the findings, our research will help policymakers to develop valuable policies for financial deepening to enhance energy green innovation.

In situfabrication of Cu-Mn-O nanostructure catalysts on Ti mesh and their catalytic property optimization for low-temperature and stable CO oxidation.

A series of interlaced 'tripe-shaped' nanoflake catalysts made of CuMn2O4werein situprepared on Ti mesh substrate through the associated methods of plasma electrolyte oxidation and hydrothermal technique. The surface morphology, elemental distribution and chemical state, phase composition and microstructure of CuMn2O4nanostructures prepared under different conditions were systemically investigated. To evaluate the catalytic activity, the CO oxidation as a probe reaction was used, and the results showed that 12h-Cu1Mn2-300 (hydrothermal reaction at 150 °C for 12 h, Cu/Mn = 1/2 in initial precursor, heat treatment temperature at 300 °C) exhibited the best CO oxidation capability withT100= 150 °C owe to the formation of uniform CuMn2O4nanosheet layersin situgrown on flexible Ti mesh and the synergistic effect of Cu and Mn species in spinel CuMn2O4, which makes it more active towards CO oxidation than pure copper/manganese oxides.

Probing the role of surface activated oxygen species of CeO2 nanocatalyst during the redox cycle in CO oxidation.

The oxygen species of CeO2 nanocatalysts plays a key role in the CO oxidation. In this work, nanocrystalline CeO2 with infrared spectroscopy detectable surface superoxide (O2 -) species at room temperature is fabricated and CO oxidation is used as a probe reaction for the exploration of the characteristics of surface O2 - species on the CeO2 surface. We discover that the surface O2 - species have ignorable influences on the overall reaction rate of CO oxidation on pure ceria by comparing P-CeO2 (CeO2 prepared by precipitation method) with HT-CeO2 (CeO2 prepared by hydrothermal method). It is concluded that the reaction between CO molecules and surface O2 - species is the first and the fast step in the whole redox cycle, while the release of surface lattice oxygen is the second and the rate determining step of the catalysts. This work gives an intuitionistic exploration on the redox properties of pure nanocrystalline CeO2 with surface O2 - species and reveals the influences of these species in the whole redox circle of CO oxidation.

Wearable biosensors for real-time sweat analysis and body motion capture based on stretchable fiber-based triboelectric nanogenerators.

Carbon neutrality is a global green energy revolution meaning that the carbon dioxide can make ends meet. However, with the mushroom of the fifth generation wireless systems (5G) and the Internet of Things (IoT), it is a great challenge for powering the ubiquitous distributed devices, because the battery production and high overhead maintenance may bring more carbon emissions. Here, we present wearable biosensors for real-time sweat analysis and body motion capture based on stretchable fiber-based triboelectric nanogenerators (F-TENG). The F-TENG is made of stretchable conductive fiber (Ecoflex coating with polyaniline (PANI)) and varnished wires. Based on the coupling effect of triboelectric effect and enzymatic reaction (surface-triboelectric coupling effect), the wearable biosensors can not only precisely sense the motion states, but also detect glucose, creatinine and lactate acid in sweat in real-time. Importantly, the wearable devices can self-drive without any external power source and the response against glucose, creatinine and lactate acid can be up to 103%, 125% and 38%, respectively. On this basis, applications in biosensing and wireless communication have been demonstrated. This work exhibits a prospective potential application of F-TENG in IoT for diverse use.

Homogeneous and well-aligned GaN nanowire arrays via a modified HVPE process and their cathodoluminescence properties.

In this work, we demonstrate the growth of homogeneous and well-aligned [0001]-oriented 1-D GaN nanoarrays via a modified hydride vapor phase epitaxy (HVPE) process using GaCl3 and NH3 as precursors. The density and length of the grown nanowires can be easily controlled by the process parameters. It was found that the growth technique provides Cl-rich growth conditions, which lead to special morphology and optical properties of the GaN nanoarrays. Different from reported GaN nanowires, the as-synthesized GaN nanoarrays in this study exhibit a hollow bamboo-like structure. Also, the cathodoluminescence spectrum shows strong visible luminescence between 400 and 600 nm wavelengths centered at 450 nm, and the disappearance of an intrinsic emission peak, which has been investigated in detail with the assistance of first-principles calculations. The strategy proposed in this work will pave a solid way for the controlled nucleation and growth of well-aligned GaN nanowire arrays which are significant for applications in large-scale integrated optoelectronic nanodevices, functionalized sensors and photoelectrocatalysis.

Catalyst-assisted heteroepitaxial strategy for highly orderedß-Ga2O3nanoarrays and their optical property investigation.

In this work, we demonstrate the growth of highly orderedß-Ga2O3nanoarrays with (001) preferred growth plane for the first time through a facile heteroepitaxial strategy using metal Ga and c-sapphire as Ga precursor and monocrystalline substrate. The (001) preferred growth plane means that theß-Ga2O3nanowires grow along the normal direction of the (001) plane. Theß-Ga2O3nanoarrays along (001) preferential plane exhibit inclined six equivalent directions that correspond to the six crystallographic symmetry of (0001)α-Al2O3. High-resolution transmission electron microscopy analyses confirm the good crystallinity and the existence of unusual epitaxial relationship of {310}ß-Ga2O3ǁ (0001)α-Al2O3and <001>ß-Ga2O3or <132>ß-Ga2O3ǁ [11¯00]α-Al2O3. UV-vis and cathodoluminescence measurements reveal the wide band gap of 4.8 eV and the strong UV-blue luminescence (300-500 nm) centered at ∼388 nm. Finally, the luminescence mechanism is further investigated with the assistance of x-ray photoelectron spectroscopy. The heteroepitaxial strategy of highly orderedß-Ga2O3nanoarrays in this work will undoubtedly pave a solid way toward the fundamental research and the applications of Ga2O3nanodevices in optoelectronic, gas sensor, photocatalyst and next-generation power electronics.

NH4F-Induced Morphology Control of CoP Nanostructures to Enhance the Hydrogen Evolution Reaction.

Developing non-noble metal catalysts with superior catalytic activity and excellent durability is critically essential to promote electrochemical water splitting for hydrogen production. Morphology control as a promising and effective strategy is widely implemented to change the surface atomic coordination and thus enhance the intrinsic catalytic performance of current electrocatalysts. Herein, a series of cobalt phosphide (CoP) electrocatalysts with tunable morphologies of nanosheets, nanowires, nanorods, and nanoblocks have been prepared for the enhanced hydrogen evolution reaction (HER) by only adjusting the amount of ammonium fluoride (NH4F) in the hydrothermal process. Benefiting from the large active area, high surface activity, and favorable ion and gas diffusion channels, the clustered CoP nanorods obtained at a concentration of 0.15 M NH4F show the best HER performance with only an overpotential of 71 mV at a current density of 10 mA cm-2 and a low Tafel slope of 60.75 mV dec-1 in 1 M KOH. After 3000 CV cycles and 24 h durability tests, there is only a very slight degradation of performance owing to its outstanding stability and robust substrate adhesion.

A Portable and Flexible Self-Powered Multifunctional Sensor for Real-Time Monitoring in Swimming.

A portable and flexible self-powered biosensor based on ZnO nanowire arrays (ZnO NWs) and flexible PET substrate has been designed and fabricated for real-time monitoring in swimming. Based on the piezoelectric effect of polar ZnO NWs, the fabricated biosensor can work in both air and water without any external power supply. In addition, the biosensor can be easily attached to the surface of the skin to precisely monitor the motion state such as joint moving angle and frequency during swimming. The constant output piezoelectric signal in different relative humidity levels enables actual application in different sports, including swimming. Therefore, the biosensor can be utilized to monitor swimming strokes by attaching it on the surface of the skin. Finally, a wireless transmitting application is demonstrated by implanting the biosensor in vivo to detect angiogenesis. This portable and flexible self-powered biosensor system exhibits broad application prospects in sport monitoring, human-computer interaction and wireless sport big data.

Design and Integration of a Layered MoS2/GaN van der Waals Heterostructure for Wide Spectral Detection and Enhanced Photoresponse.

Molybdenum disulfide (MoS2) as a typical two-dimensional (2D) transition-metal dichalcogenide exhibits great potential applications for the next-generation nanoelectronics such as photodetectors. However, most MoS2-based photodetectors hold obvious disadvantages including a narrow spectral response in the visible region, poor photoresponsivity, and slow response speed. Here, for the first time, we report the design of a two-dimensional MoS2/GaN van der Waals (vdWs) heterostructure photodetector consisting of few-layer p-type MoS2 and very thin n-type GaN flakes. Thanks to the good crystal quality of the 2D-GaN flake and the built-in electric field in the interface depletion region of the MoS2/GaN p-n junction, photogenerated carriers can be rapidly separated and more excitons are collected by electrodes toward the high photoresponsivity of 328 A/W and a fast response time of 400 ms under the illumination of 532 nm light, which is seven times faster than pristine MoS2 flake. Additionally, the response spectrum of the photodetector is also broadened to the UV region with a high photoresponsivity of 27.1 A/W and a fast response time of 300 ms after integrating with the 2D-GaN flake, exhibiting an advantageous synergetic effect. These excellent performances render MoS2/GaN vdWs heterostructure photodetectors as promising and competitive candidates for next-generation optoelectronic devices.

Investigation of catalyst-assisted growth of nonpolar GaN nanowires via a modified HVPE process.

The growth of nonpolar GaN nanowires along the [101[combining macron]0] orientation has been demonstrated via a modified hydride vapor phase epitaxy (HVPE) process using GaCl3 and NH3 as precursors. The morphology and structure evolution as a dependence of the growth parameters was thoroughly studied to elucidate the nucleation and crystallization of nonpolar GaN nanowires. It has been found that the V/III ratio and temperature are critically important for the formation of high-quality nonpolar GaN nanowires. The existence of a cubic GaN (c-GaN) transition layer between the Au catalyst and hexagonal GaN (h-GaN) nonpolar nanowires was demonstrated by high-resolution transmission electron microscopy (HRTEM) characterization, which plays an important role in the initial nucleation of nonpolar GaN nanowires and the formation of stacking faults (SFs) in the GaN nanowires grown at lower temperature. Optical investigations show that the defect-related visible emission of nonpolar GaN nanowires is closely related to the growth process and can be selectively tailored. The synthetic strategy using GaCl3 as the Ga precursor to study the vapor phase epitaxy process in this work will provide a simple and efficient approach to obtain nonpolar GaN nanowires and will thus pave a solid way for fundamental research on high-quality nonpolar GaN nanowires in optoelectronic nanodevices.

Simultaneous detection of trace Ag(I) and Cu(II) ions using homoepitaxially grown GaN micropillar electrode.

Driven by the motivation to quantitively control and monitor trace metal ions in water, the development of environmental-friendly electrodes with superior detection sensitivity is extremely important. In this work, we report the design of a stable, ultrasensitive and biocompatible electrode for the detection of trace Ag+ and Cu2+ ions by growing n-type GaN micropillars on conductive p-type GaN substrate. The electrochemical measurement based on cyclic voltammetry indicates that the GaN micropillars exhibit quasi-reversible and mass-controlled reaction in redox probe solution. In the application of trace Ag+ and Cu2+ determination, the GaN micropillars show superior sensitivity and excellent conductivity by presenting a detection limit of 3.3 ppb for Ag+ and 3.3 ppb for Cu2+. Comparative studies on the electrochemical response of GaN micropillars and GaN film in the simultaneous Ag+ and Cu2+ detection reveal that GaN micropillars show three orders of magnitude higher stripping peak current than GaN film. It is assumed that the microarray morphology with large active area and the hydrophilia nature of GaN micropillars are responsible for the excellent sensitivity. This work will open up some opportunities for GaN nanostructure electrodes in the application of trace metal ions detection.

Band-Gap Tunable 2D Hexagonal (GaN)1-x(ZnO)x Solid-Solution Nanosheets for Photocatalytic Water Splitting.

A (GaN)1-x(ZnO)x solid solution as a promising visible-light-driven photocatalyst for overall water splitting has attracted extensive attention. In this work, we proposed a template reactive strategy toward the synthesis of band-gap tunable 2D (GaN)1-x(ZnO)x nanosheets as thin as 14 nm to reduce the carrier transportation path and thus efficiently decrease the recombination of electrons and holes. It is demonstrated that the template strategy enables an ideal morphology and structure transformation from hexagonal 2D ZnGa2O4 nanosheets to 2D (GaN)1-x(ZnO)x nanosheets in the nitridation process. After the modification of 1 wt % of Rh cocatalyst, the flowerlike (GaN)0.89(ZnO)0.11 nanosheets show an enhanced hydrogen evolution in pure water (pH 4.5).

Cu3P-Ni2P Hybrid Hexagonal Nanosheet Arrays for Efficient Hydrogen Evolution Reaction in Alkaline Solution.

The development of efficient and low-cost hydrogen evolution reaction electrocatalysts has been regarded as a promising approach to produce sustainable and clean fuels to solve the energy crisis and environmental problems. Herein, 3D hybrid Cu3P-Ni2P hexagonal nanosheet arrays are successfully prepared on nickel foam (Cu3P-Ni2P/NF). Benefiting from synergistic effects and strong chemical coupling existing at the interface, the Cu3P-Ni2P/NF electrode exhibits a low overpotential of 103 mV at a current density of 10 mA cm-2, which is 47 and 100 mV less than that for Ni2P/NF and Cu3P/NF, respectively. It also shows excellent electrochemical durability for long-term reaction in alkaline medium. The excellent electrocatalytic activity makes the Cu3P-Ni2P/NF as a promising cathode toward efficient hydrogen evolution via electrochemical water splitting.

High-Performance Flexible Ultraviolet Photodetectors Based on AZO/ZnO/PVK/PEDOT:PSS Heterostructures Integrated on Human Hair.

Flexible optoelectronics is an emerging research field that has attracted a great deal of interest in recent years due to the special functions and potential applications of these devices in flexible image sensors, optical computing, energy conversion devices, the Internet of Things, and other technologies. Here, we examine the high-performance ultraviolet (UV) photodetectors using AZO/ZnO nanorods/PVK/PEDOT:PSS heterostructures integrated on human hair. Due to the precise interfacial energy-level alignment among all layers and superior mechanical characteristics of human hair, the as-obtained photodetector shows a fast response time, high photoresponsivity, and excellent flexibility. According to integrate 7 heterostructures as 7 display pixels, the flexible UV-image sensor has superior device performance and outstanding flexibility and can produce vivid and accurate images of Arabic numerals from 0 to 9. Different combinations of the two heterostructures can also be used to achieve flexible photon-triggered logic functions, including AND, OR, and NAND gates. Our findings indicate the possibility of using human hair as a fiber-shaped flexible substrate and will allow the use of hair-based hierarchical heterostructures as building blocks to create exciting opportunities for next-generation high-performance, multifunctional, low-cost, and flexible optoelectronic devices.

Hydrothermal Approach to Spinel-Type 2D Metal Oxide Nanosheets.

The peculiar physical and chemical properties of 2D nanostructures have aroused global research interest in developing new members, synthetic technology, and exploring their potential applications in functional nanodevices. However, it is extremely challenging to directly obtain the 2D nanosheets for these extrinsic layered structures using conventional routines. In this work, we demonstrate the facile and general synthesis of 2D spinel-type metal oxides nanosheets through a simple hydrothermal reaction. Using this method, cubic γ-Ga2O3, ZnGa2O4 and MnGa2O4 nanosheets with triangular/hexagonal configuration and ultrathin thickness have been synthesized, and all these nanosheets show preferential growth along (111) plane with the minimum formation energy. Microstructural and composition analyses using HRTEM, EDS, XPS, and so on reveal that the as-synthesized 2D nanosheets are well-crystallized in cubic fcc-phase and show high purity in composition, and the formation process of MGa2O4 nanosheets can be regarded as the competition of M2+ and Ga3+ in tetrahedral site. Spatially resolved cathodoluminescence measurement of individual 2D nanosheet shows that the γ-Ga2O3, ZnGa2O4, and MnGa2O4 nanosheets exhibit distinct luminescence behavior, and ZnGa2O4 nanosheets show the strongest emission in visible region. It is expected that the facile synthesis of spinel-type metal oxides of γ-Ga2O3, ZnGa2O4, and MnGa2O4 nanosheets will further promote the exploration of a variety of semiconductor nanostructures that could not be achieved using conventional technology suitable for layered structures and will also open up some opportunities for the integration of advanced functional nanodevices such as photodetectors, phosphors on the basis of them.

Multi-wavelength tailoring of a ZnGa2O4 nanosheet phosphor via defect engineering.

The multi-wavelength luminescence tailoring of an individual phosphor free of external dopants is of great interest and technologically important for practical applications. Using ZnGa2O4 nanosheets as a target phosphor, we demonstrate how to artificially control the luminescence wavelength centers and their emission intensities to simultaneously emit ultraviolet/blue, green and red light via a feasible defect engineering strategy. Simple high-temperature annealing of hydrothermally synthesized ZnGa2O4 nanosheets leads to the effective tunability of their emission process to present multi-wavelength luminescence due to the structural distortion and the formation of oxygen vacancies. Controlling the annealing temperature and time can further precisely modulate the wavelengths and their corresponding intensities. It is speculated that the migration of Ga into the [GaO4] tetrahedron and the O vacancy are responsible for the multi-wavelength luminescence of the ZnGa2O4 nanosheet phosphor. Finally, the tentative multi-wavelength luminescence behavior of the ZnGa2O4 nanosheet phosphor via defect engineering is discussed based on a series of evidenced experimental observations of XRD, XPS, HRTEM and CL.

Formation of ZnCo2O4@MnO2 core-shell electrode materials for hybrid supercapacitor.

In this work, ZnCo2O4@MnO2 core-shell structures are successfully prepared on nickel foam by a simple hydrothermal approach. The obtained core-shell structures exhibit excellent areal capacitance and cycling stability, which may be ascribed to the rational design of a hybrid-material based electrode structure that facilitates ion transport. The as-assembled supercapacitor device shows outstanding specific capacitance, demonstrating that ZnCo2O4@MnO2 core-shell structure is a candidate as a supercapacitor electrode material in flexible energy storage applications.

Composition and Band Gap Tailoring of Crystalline (GaN)1- x(ZnO) x Solid Solution Nanowires for Enhanced Photoelectrochemical Performance.

Photoelectrochemical water splitting has emerged as an effective artificial photosynthesis technology to generate clean energy of H2 from sunlight. The core issue in this reaction system is to develop a highly efficient photoanode with a large fraction of solar light absorption and greater active surface area. In this work, we take advantage of energy band engineering to synthesize (GaN)1- x(ZnO) x solid solution nanowires with ZnO contents ranging from 10.3% to 47.6% and corresponding band gap tailoring from 3.08 to 2.77 eV on the basis of the Au-assisted VLS mechanism. The morphology of nanowires directly grown on the conductive substrate facilitates the charge transfer and simultaneously improves the surface reaction sites. As a result, a photocurrent approximately 10 times larger than that for a conventional powder-based photoanode is obtained, which indicates the potential of (GaN)1- x(ZnO) x nanowires in the preparation of superior photoanodes for enhanced water splitting. It is anticipated that the water-splitting capability of (GaN)1- x(ZnO) x nanowire can be further increased through alignment control for enhanced visible light absorption and reduction of charge transfer resistance.