Suppressing gas swelling in self-assembled Li4Ti5O12 (400) for high-performance rechargeable batteries.

Lithium titanate is a promising anode material for lithium-ion batteries due to its high-rate capability and long-cycle duration. However, gas swelling during electrochemical reactions has hindered its industrial application. Here, we synthesize self-assembled (400)-orientation lithium titanate (SA-LTONF) with ultrafine nanoparticles using a feasible thermal method. The SA-LTONF with an organic carbon coating exhibited superior electrochemical performance. To understand such high-rate capability, we perform density functional theory (DFT) calculations which elucidate the orientation-dependent electrochemical mechanism of hydrogen evolution and the atomically dynamic mechanism of lithium-ion migration in Li4Ti5O12 and Li7Ti5O12. Our findings provide a unique insight into the gas generation and ultrafast lithium-ion transportation in lithium titanate and offer guidance for nanoarchitecture construction and materials design of lithium titanate for commercial applications.

Impact of green credit on green economy efficiency in China.

With urgent desire of promoting sustainable development, this study explored the impact and affecting mechanism of green credit on green economy efficiency through spatial lag model. Panel data from 2008 to 2019 of 30 selected provinces and cities in China were collected to portray the green economy efficiency with application of Sup-SBM DEA including unexpected outputs. The results show that (1) green credit had significant promoting effect on green economy efficiency, while time-space inconsistency existed. (2) During the promoting process, level of marketization and environmental regulation generated threshold effects, which were positively correlated with regional green economy efficiency. (3) Industrial structure upgrading and environmental investment played positive intermediary roles between green credit and green economy efficiency. (4) Considering endogenous issues, the positive effect still existed though the promotion effect was weakened. This study further enriches the literature and provides deep insights into the policy design when formulating the green economy path.

Nucleation and growth mechanisms of an electrodeposited Ni-Se-Cu coating on nickel foam.

Electrocatalysts for water splitting have been widely explored among recent years. In this study, nickel-selenium-copper (Ni-Se-Cu) coating was synthesized on nickel foam through potentiostatic electrodeposition. The electrochemical kinetics and nucleation mechanisms of the deposition were investigated, and the diffusion coefficient D from different deposition potentials and temperatures was calculated. Results reveal that the electrodeposition of Ni-Se-Cu follows an instantaneous nucleation and diffusion-controlled three-dimensional (3D) growth mechanism. Deposition potential and bath temperature slightly effect the nucleation mechanism of electrodeposition. The apparent activation energy Ea of the hydrogen evolution reaction (HER) in 1.0 M KOH electrolyte of Ni-Se-Cu is 21.1 kJ·mol-1, which is lower than that of Ni-Se (37.7 kJ·mol-1). The majority phase formed by nickel and selenium is Ni3Se2, and a Ni(Cu) solid solution forms after the incorporation of Cu atoms into a Ni lattice.

Potentiostatic electrodeposition of Ni-Se-Cu on nickel foam as an electrocatalyst for hydrogen evolution reaction.

Development of cost-effective and efficient earth-abundant catalysts for hydrogen evolution reaction (HER) is a great challenge. In this study, by one-step potentiostatic electrodeposition, the Ni-Se-Cu electrocatalyst on nickel foam was fabricated as a binder-free HER electrocatalyst. As compared with Ni-Se electrocatalysts, such fabricated Ni-Se-Cu electrocatalyst exhibited prominent electrocatalytic activity to the HER in alkaline electrolyte. This Ni-Se-Cu electrocatalyst exhibits a small overpotential of 136 mV to achieve a current density of 10 mA·cm-2 and high electrochemical stability. The remarkable HER properties of Ni-Se-Cu electrocatalyst mainly originate from high electronic conductivity induced by Cu-doping. This work shows a cheap and simple avenue to develop high efficient non-noble electrochemical electrocatalysts for HER.