RESUMO

The sluggish dissociation of water in alkaline electrolytes significantly hinders the kinetics of the hydrogen evolution reaction (HER), particularly on surfaces of Ru-based catalysts. The structure of water at the water-catalyst interface influences this dissociation process, yet controlling the configuration of water molecules is challenging due to their random distribution. In this study, a NiRu alloy supported on nitrogen-doped carbon (NiRu/NC) is selected as a model catalyst to investigate the electron distribution of the catalyst manipulating the adsorption configuration and orientation of water molecules. The introduction of Ni leads to charge transfer from Ni to Ru atoms within the NiRu alloy, causing a notable redistribution of charge that strengthens the local electric fields surrounding the NiRu alloy. These electron-rich Ru sites attract K+ cations to the surface, resulting in an increased presence of K+ cation-hydrated water molecules, which is an H-down configuration with a reduced Ru-H distance. This phenomenon is confirmed by in situ Raman spectroscopy. Consequently, NiRu/NC exhibits outstanding HER performance, achieving low overpotentials of 16 and 344 mV at current densities of 10 and 1000 mA cm-2, respectively.

RESUMO

Rechargeable Zn-air batteries (ZABs) are promising for energy storage and conversion. However, the high charging voltage and low energy efficiency hinder their commercialization. Herein, these challenges are addressed by employing precisely constructed multifunctional Fe-Co diatomic site catalysts (FeCo-DACs) and integrating iodide/iodate redox into ZABs to create Zinc-air/iodide hybrid batteries (ZAIHBs) with highly efficient multifunctional catalyst. The strong coupling between the 3d orbitals of Fe and Co weakens the excessively strong binding strength between active sites and intermediates, enhancing the catalytic activities for oxygen reduction/evolution reaction and iodide/iodate redox. Consequently, FeCo-DACs exhibit outstanding bifunctional oxygen catalytic activity with a small potential gap (ΔE = 0.66 V) and outstanding stability. Moreover, an outstanding catalytic performance toward iodide/iodate redox is obtained. Therefore, FeCo-DAC-based ZAIHBs exhibit high energy efficiency of up to 75% at 10 mA cm-2 and excellent cycling stability (72% after 500 h). This research offers critical insights into the rational design of DACs and paves the way for high-energy efficiency energy storage devices.

RESUMO

The exploitation of an extraordinary and low-cost electrocatalyst to solve energy shortage and environmental pollution issues is crucial. Herein, a topological Archimedean polyhedron of CoFe PBA (Prussian blue analogue) was synthesized via a Sn-induced crystal growth regulation strategy. After phosphating treatment of the as-prepared Sn-CoFe PBA, a Sn-doped binary CoP/FeP hybrid was obtained (Sn-CoP/FeP). Benefiting from the rough polyhedral surface and internal porous structure of Sn-CoP/FeP, when served as a highly efficient electrocatalyst, it exhibited outstanding HER performance, i.e., to drive a current density of 10 mA cm-2, it required a low overpotential of 62 mV in alkaline medium, along with a long-term cycling stability for 35 h. This work is of great significance for the development of indispensable novel catalysts for hydrogen production, and would shed new light on the topology-related performance of electrocatalysts for energy storage and conversion.

RESUMO

The Clean Air Plan has been active in China since 2013 to mitigate severe PM2.5 pollution. In this study, we applied the air quality model WRF-Chem to simulate PM2.5 in the Yangtze River Delta (YRD) region of China in 2017, with the aim of assessing the air quality improvement and its associated health burden in the final year of the Clean Air Plan. To better describe the fate of various PM2.5 compositions, we updated the chemical mechanisms in the model beforehand, including heterogeneous sulfate reactions, aqueous secondary organic aerosol (SOA) uptake, and volatility basis set (VBS) based SOA production. Both the observation and simulation results agreed that the stringent clear air action effectively reduced the PM2.5 pollution levels by âˆ¼ 30 %. The primary PM2.5 (-6 âˆ¼  - 16 % yr-1) showed a more significant decreasing trend than the secondary PM2.5 (-2 âˆ¼  - 8 % yr-1), which was mainly caused by the directivity of the clear air actions and the worsening ozone pollution in the recent years. The inconsistent decreasing trends of PM2.5 components subsequently led to an increasing proportion of secondary PM2.5. Nitrate particles, higher in the central and western YRD region, have replaced sulfate and have become the largest component of secondary inorganic aerosols year-round, except in summer, when strong ammonium nitrate evaporation occurs. In addition, SOA remains an important component (21 âˆ¼ 22 %) especially in summer, most of which is produced from the oxidation and ageing of semi/intermediate volatile organic compounds (S/IVOC). Furthermore, we quantified the associated health impacts and found that the Clean Air Plan has largely reduced premature mortality due to PM2.5 exposure in the YRD region from 399.1 thousand to 295.7 thousand. Our study highlights the benefits of the Clean Air Plan and suggests that subsequent PM2.5 improvement should be geared more towards controlling secondary pollutants.

Assuntos

Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Material Particulado/análise , Monitoramento Ambiental , China , Aerossóis/análise , Estações do Ano , Sulfatos/análise

RESUMO

Design and fabrication of bifunctional efficient and durable noble-metal-free electrocatalyst for hydrogen and oxygen evolution is highly desirable and challenging for overall water splitting. Herein, a novel hybrid nanostructure with Ni2P/CoP nanoparticles decorated on a porous N-doped fullerene nanorod (p-NFNR@Ni-Co-P) was developed as a bifunctional electrocatalyst. Benefiting from the electric current collector (ECC) effect of FNR for the active Ni2P/CoP nanoparticles, the p-NFNR@Ni-Co-P exhibited outstanding electrocatalytic performance for overall water splitting in alkaline medium. To deliver a current density of 10 mA cm-2, the electrolytic cell assembled by p-NFNR@Ni-Co-P merely required a potential as low as 1.62 V, superior to the benchmark noble-metal-based electrocatalyst. Experimental and theoretical results demonstrated that the surface engineered FNR serving as an ECC played a critical role in accelerating the charge transfer during the electrocatalytic reaction. The present work paves the way for fullerene nanostructures in the realm of energy conversion and storage.