This study investigates the impact of environmental regulations (ERs) and foreign direct investment (FDI) on the green total factor productivity (GTFP) of the industrial sectors in 30 provinces in ...China by controlling human capital, technological innovation, energy structure, degree of opening up, and ownership structure for the period of 2004–2017. This not only helps to explain the influence path of ERs and FDI on green economic growth, but also effectively measures the moderating effect of ERs on technology spillover from FDI. The purpose of this paper is to explore the relationship between ERs, FDI and industrial GTFP from the perspective of regional heterogeneity, focusing on studying how ERs regulate the impact of FDI on GTFP. By constructing an influence mechanism of ERs and FDI on industrial GTFP, this study employs the feasible generalized least squares (FGLS) model and dynamic generalized method of moments (GMM) model to analyze the effects of ERs, FDI and their cross-terms on GTFP. The empirical results show that (1) the relationship between ERs and GTFP is not linear, but “U”-shaped and China is still in the left half of the “U”-shaped curve; (2) FDI flowing into China has a “pollution heaven” effect on the GTFP in the eastern and central regions while a “pollution halo” effect on the GTFP in the western region; (3) the strengthening of ERs weakens the negative effect of FDI on GTFP and plays a role in “screening” foreign investment; and (4) the spatial heterogeneity could affect the synergistic effect between ERs and FDI. Therefore, it is necessary for China to consider a series of environmental policies to “screen” inward FDI to ensure its move to a green economy benefits its own sustainable development by contributing to the increase in GTFP.
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•The influence mechanism of environmental regulation and FDI on GTFP is proposed.•Dynamic FGLS and GMM methods are used for empirical estimations.•Environmental regulations exhibit a significant U-shaped effect on GTFP.•FDI exerts a “pollution heaven” effect on GTFP in eastern and central China.•Environmental regulations weaken the restraining effect of FDI on GTFP.
Since the electrocatalytic activity of layered molybdenum disulfide (MoS2) for hydrogen evolution reaction (HER) closely depends on its exposed edges, the morphology and size of the material are ...critically important. Herein, we introduce a novel solvent-evaporation-assisted intercalation method to fabricate the hybrid of alternating MoS2 sheets and reduced graphene oxide layers, in which the nanosize of the MoS2 nanosheets can be effectively controlled by leveraging the confinement effect within the two-dimensional graphene layers. Significantly, the resulting MoS2/reduced graphene oxide (RGO) composite shows excellent catalytic activity for HER characterized by higher current densities and lower onset potentials than the conventional pre-exfoliated RGO supported MoS2 nanosheets. Further experiments on the effect of oxidation degree of graphene, the crystallinity of MoS2, and the exposed active site density on the HER performance of the MoS2/RGO composites show that there is an optimum condition for the catalytic activity of HER due to a balance between the numbers of exposed active sites of MoS2 and the internal conductive channels provided by graphene.
In this paper, we further investigate the constructions of complementary sequence sets (CSSs) and complete complementary codes (CCCs) by Butson-type Hadamard matrices. By taking the algebraic ...structure of Butson-type Hadamard (BH) matrices into consideration, we obtain the explicit representation of the δ-linear terms and δ-quadratic terms, which are ingredients to construct CSSs and CCCs. In particular, we derive the δ-quadratic terms determined by DFT matrices and BH matrices constructed from 2-level autocorrelation sequences, which yields two type of new contructions. We show that inequivalent BH matrices produce different CSSs and CCCs, which proves that our constructed CSSs and CCCs are new. As a consequence of the first type of the constructions, not only a large number of p -ary CSSs and CCCs of size p ( p prime) have been proposed, which were never reported in the literature, but also a theory linking these CSSs of p -ary sequences and the generalized Reed-Muller codes proposed by Kasami et al . is shown. These codes enjoy good error-correcting capability, tightly controlled PMEPR, and significantly extend the range of coding options for applications of OFDM using p n subcarriers. As a consequence of the second type of the constructions, we reveal an extremely fascinating hidden connection between the sequences in aperiodic CSSs and CCCs and the sequences with ideal period 2-level autocorrelation, through their trace representations and permutation polynomials over finite fields.
Cost‐effective electrocatalysts for the oxygen evolution reaction (OER) are critical to energy conversion and storage processes. A novel strategy is used to synthesize a non‐noble‐metal‐based ...electrocatalyst of the OER by finely combining layered FeNi double hydroxide that is catalytically active and electric conducting graphene sheets, taking advantage of the electrostatic attraction between the two positively charged nanosheets. The synergy between the catalytic activity of the double hydroxide and the enhanced electron transport arising from the graphene resulted in superior electrocatalytic properties of the FeNi‐GO hybrids for the OER with overpotentials as low as 0.21 V, which was further reduced to 0.195 V after the reduction treatment. Moreover, the turnover frequency at the overpotential of 0.3 V has reached 1 s−1, which is much higher than those previously reported for non‐noble‐metal‐based electrocatalysts.
A low‐cost and highly active electrochemical catalyst for the oxygen evolution reaction is created by alternatively stacking FeNi double hydroxide cation layers with GO anionic sheets. The advanced performance of the catalyst stems from the intrinsic catalytic activity of the layered FeNi double hydroxide and is boosted by the high electric conductivity of the adjoining graphene sheets.
The kinetically sluggish rate of oxygen reduction reaction (ORR) on the cathode side is one of the main bottlenecks of zinc‐air batteries (ZABs), and thus the search for an efficient and ...cost‐effective catalyst for ORR is highly pursued. Co3O4 has received ever‐growing interest as a promising ORR catalyst due to the unique advantages of low‐cost, earth abundance and decent catalytic activity. However, owing to the poor conductivity as a result of its semiconducting nature, the ORR activity of the Co3O4 catalyst is still far below the expectation. Herein, we report a controllable N‐doping strategy to significantly improve the catalytic activity of Co3O4 for ORR and demonstrate these N doped Co3O4 nanowires as an additive‐free air‐cathode for flexible solid‐state zinc‐air batteries. The results of experiments and DFT calculations reveal that the catalytic activity is promoted by the N dopant through a combined set of factors, including enhanced electronic conductivity, increased O2 adsorption strength and improved reaction kinetics. Finally, the assembly of all‐solid‐state ZABs based on the optimized cathode exhibit a high volumetric capacity of 98.1 mAh cm‐3 and outstanding flexibility. The demonstration of such flexible ZABs provides valuable insights that point the way to the redesign of emerging portable electronics.
A novel additive‐free design of the air‐cathode for flexible zinc–air batteries consists of directly growing and neatly assembling mesoporous Co3O4 nanowires on a carbon cloth. To optimize the catalytic activity of Co3O4 for the oxygen reduction reaction, a controllable N‐doping strategy is developed giving rise to enhanced electronic conductivity and increased O2 adsorption strength.
This study examines the relationship between economic policy uncertainty and mergers and acquisitions (M&As) in China. Using all listed Chinese companies on the Shanghai and Shenzhen Stock Exchanges ...as well as 4188 M&A deals from the period of 2001–2018, we show that Chinese firms are more likely to make acquisitions during periods of high economic policy uncertainty, which contradicts the behavior of US firms. We further show that state-owned enterprises (SOEs) are less likely than non-SOEs to make acquisitions during periods of high economic policy uncertainty. SOEs are less likely to use only cash for their acquisitions during periods of high economic policy uncertainty. These results indicate the prudence of SOEs regarding acquisitions relative to non-SOEs during periods of high economic policy uncertainty. Moreover, acquisitions during periods of high economic policy uncertainty are associated with an increase in shareholder wealth for acquirers, and this wealth effect is more pronounced for SOEs.
•We examine the relationship between economic policy uncertainty and mergers and acquisitions (M&A) in China.•Firms in China are more likely to make acquisition during periods of high economic policy uncertainty, which contradicts the behavior of US firms.•State-owned enterprises (SOEs) are less likely than non-SOEs to make acquisitions during periods of high economic policy uncertainty.•SOEs are also less likely to use only cash for their acquisitions during periods of high economic policy uncertainty.•Acquisitions during periods of high economic policy uncertainty increase shareholder wealth for acquirers, in particular, SOE acquirers.
We report on the synthesis of iron-nickel sulfide (INS) ultrathin nanosheets by topotactic conversion from a hydroxide precursor. The INS nanosheets exhibit excellent activity and stability in strong ...acidic solutions as a hydrogen evolution reaction (HER) catalyst, lending an attractive alternative to the Pt catalyst. The metallic α-INS nanosheets show an even lower overpotential of 105 mV at 10 mA/cm2 and a smaller Tafel slope of 40 mV/dec. With the help of DFT calculations, the high specific surface area, facile ion transport and charge transfer, abundant electrochemical active sites, suitable H+ adsorption, and H2 formation kinetics and energetics are proposed to contribute to the high activity of the INS ultrathin nanosheets toward HER.
A new method to construct <inline-formula> <tex-math notation="LaTeX">q </tex-math></inline-formula>-ary complementary sequence sets (CSSs) and complete complementary codes (CCCs) of size ...<inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula> is proposed by using desired para-unitary (PU) matrices. The concept of seed PU matrices is introduced and a systematic approach on how to compute the explicit forms of the functions in constructed CSSs and CCCs from the seed PU matrices is given. A general form of these functions only depends on a basis of the functions from <inline-formula> <tex-math notation="LaTeX">{\mathbb Z}_{N} </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">{\mathbb Z}_{q} </tex-math></inline-formula> and representatives in the equivalent class of Butson-type Hadamard (BH) matrices. Especially, the realization of Golay pairs from our general form exactly coincides with the standard Golay pairs. The realization of ternary complementary sequences of size 3 is first reported here. For the realization of the quaternary complementary sequences of size 4, almost all the sequences derived here are never reported before. Generalized seed PU matrices and the recursive constructions of the desired PU matrices are also studied, and a large number of new constructions of CSSs and CCCs are given accordingly. From the perspective of this paper, all the known results of CSSs and CCCs with explicit GBF form in the literature (except non-standard Golay pairs) are constructed from the WHT matrices. This suggests that the proposed method with other BH matrices will yield a large number of new CSSs and CCCs with the significantly increasing number of the sequences of low peak-to-mean envelope power ratio.
Here, we demonstrate that carbon quantum dots (CQDs), as a low cost, chemically stable, and environmentally friendly photosensitizer, can dramatically broaden the light absorption range to the entire ...visible range. Consequently, the NiOOH/FeOOH/CQD/BiVO4 (NFCB) photoanode has achieved a remarkable photocurrent density of 5.99 mA cm-2 at 1.23 V vs. RHE under AM 1.5G in KH2PO4 aqueous solution without a hole scavenger (pH = 7) and a record high applied bias photon-to-current efficiency of 2.29% at 0.6 V vs. RHE for BiVO4-based photoanodes. This novel NFCB photoanode could operate stably for 10 h with a Faraday efficiency of similar to 95%, demonstrating the great potential of using CQDs for solar water splitting.
Rural areas are often overlooked in discussions of how best to achieve net zero CO2 emissions (CEs) by mid-century, thereby attaining one of the main goals of the 2015 Paris Agreement. This is ...particularly the case for residential areas in rural areas, which in some countries account for a considerable proportion of the total population and thus domestic CEs. Using data from 29 provinces in China during the period of 2007–2018 and spatial regression models, this study investigates the relationship between rural renewable energy and residential fossil energy-related CEs. Over 500 million people currently reside in rural areas in China. The results indicate: (1) significant regional differences in rural renewable energy and residential CEs, as a result of a combination of environmental and socio-economic factors; (2) a negative association between rural residential CEs and uptake of solar water heaters and biogas digesters (a 1% increase in the use of solar water heaters is associated with a 0.3% decline in residential CEs); and (3) the importance of rural renewable energy, industrial upgrading, economic development, and technological innovation in indirectly influencing residential CEs, with spillover effects. These findings provide evidence for a relatively low-cost solution to the challenge of transitioning to net zero domestic CEs in rural areas in China and indeed more generally.
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•Rural residential CO2 emissions (CEs) and renewable energy use in China show distinct regional disparities.•Rural residential CEs were negatively associated with uptake of solar water heaters and biogas digesters.•Rural renewable energy exhibited a spillover effect on residential CEs.•IPAT theory is applicable to this study.
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