No abstract

Ammonia is an important chemical raw material, widely used in industry and agriculture, as well as an important energy storage intermediate and carbon‐free energy carrier. But, its production is limited to the traditional Haber‐Bosch process. Recently, electrochemical reduction of N2 has been attracting more and more attention, owing to the lower energy consumption and because it is environmentally friendly. However, there are a lot of problems that remain to be solved, and the main challenges are the low selectivity and catalytic activity when using this process. In this Review, we first summarize the recent development of electrocatalysts for electrochemical N2 reduction and elaborate on the reaction mechanisms of the nitrogen reduction reaction (NRR). In addition, the effects of different types of electrolyte on the NRR activity and electrolyte choice are discussed. Finally, the perspectives of electrochemical nitrogen reduction for conversion to ammonia are discussed.

No abstract

Considering consumers are increasingly shopping online nowadays and the online sales market is dominated by e‐commerce giants, traditional retailers need to choose whether to enter e‐commerce platforms. Moreover, traditional retailers need to determine whether to offer offline return services considering online return services are very popular. To address these challenges, we explore a retailer's optimal offline return strategy and channel choice of whether or not to enter a platform in the contexts of symmetric information and asymmetric information, respectively. We present conditions for the retailer to share information. Interestingly, we find that the retailer in some conditions has no motivation to improve customer satisfaction rate of offline store. Most important, we find that the retailer's channel choice depends on the magnitude of the annual service fee that is affected by offline return strategy and asymmetric information, and the offline return strategy depends on the magnitude of the average residual value of returned products.

It remains a tremendous challenge to develop a low‐cost, earth‐abundant, and efficient catalyst with multifunctional activities for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). Herein, a facile and scalable avenue was developed to prepare amorphous Co−P/Co−N−C supported on N, P co‐doped porous carbon (Co−P/Co−N−C/NPC) with a large specific surface area (1462.9 m2 g−1) and abundant reactive sites including Co−P, Co−N and NPC. The prepared electrocatalyst exhibits outstanding catalytic performance for HER (η=234 mV at 10 mA cm−2), OER (η=374 mV at 10 mA cm−2), and ORR (E1/2=0.89 V, vs. reversible hydrogen electrode). Benefiting from the excellent HER performance and outstanding OER activity, the Co−P/Co−N−C/NPC delivers a current density of 10 mA cm−2 for overall water splitting at a cell voltage of 1.59 V, which is comparable with the IrO2–Pt/C couple electrode.

To highlight the differences in water quality impacts of different indicators in water samples, this paper proposes a grey clustering method based on improved analytic hierarchy process to evaluate the quality of surface water. According to the pollution degree of different indicators in the water quality sample, the importance score is assigned, and the weight of different indicators is calculated by the analytic hierarchy process. The weight participates in the calculation of the grey clustering coefficient, and the evaluated water quality category considers the difference of the contribution rate of different pollutant indicators. The water quality samples of three water periods (Abundant, Normal, and Poor water flow periods) in the four sections of Qingshui River in Duyun City (Tea garden, Youhang, Yingpan and Jiadeng) were selected for evaluation, and the conventional grey clustering method and single factor method were used. The evaluation results were compared and analyzed. The evaluation results show that the improved grey clustering method is more scientific and reasonable and can provide a basis for water quality assessment and water environment management of water environment management departments.

No abstract

NiWO4 was prepared through a facile and large-scale strategy, and exhibited superior electrocatalytic performance, relative to NiO and WO3, for the nitrogen reduction reaction in both acidic and alkaline media at room temperature.