As one of the world’s most produced chemicals, ammonia (NH3) is synthesized by Haber–Bosch process. This century-old industry nourishes billions of people and promotes social and economic development. In the meantime, 3%–5% of the world’s natural gas and 1%–2% of the world’s energy reserves are consumed, releasing millions of tons of carbon dioxide annually to the atmosphere. The urgency of replacing fossil fuels and mitigating climate change motivates us to progress toward more sustainable methods for N2 reduction reaction based on clean energy. Herein, we overview the emerging advancement for sustainable N2 fixation under mild conditions, which include electrochemical, photo- , plasma-enabled and homogeneous molecular NH3 productions. We focus on NH3 generation by electrocatalysts and photocatalysts. We clarify the features and progress of each kind of NH3 synthesis process and provide promising strategies to further promote sustainable ammonia production and construct state-of-the-art catalytic systems.
Grid-level large-scale electrical energy storage (GLEES) is an essential approach for balancing the supply–demand of electricity generation, distribution, and usage. Compared with conventional energy storage methods, battery technologies are desirable energy storage devices for GLEES due to their easy modularization, rapid response, flexible installation, and short construction cycles. In general, battery energy storage technologies are expected to meet the requirements of GLEES such as peak shaving and load leveling, voltage and frequency regulation, and emergency response, which are highlighted in this perspective. Furthermore, several types of battery technologies, including lead–acid, nickel–cadmium, nickel–metal hydride, sodium–sulfur, lithium-ion, and flow batteries, are discussed in detail for the application of GLEES. Moreover, some possible developing directions to facilitate efforts in this area are presented to establish a perspective on battery technology, provide a road map for guiding future studies, and promote the commercial application of batteries for GLEES.
Phosphorus in energy storage has received widespread attention in recent years. Both the high specific capacity and ion mobility of phosphorus may lead to a breakthrough in energy storage materials. Black phosphorus, an allotrope of phosphorus, has a sheet-like structure similar to graphite. In this review, we describe the structure and properties of black phosphorus and characteristics of the conductive electrode material, including theoretical calculation and analysis. The research progress in various ion batteries, including lithium-sulfur batteries, lithium–air batteries, and supercapacitors, is summarized according to the introduction of black phosphorus materials in different electrochemical applications. Among them, with the introduction of black phosphorus in lithium-ion batteries and sodium-ion batteries, the research on the properties of black phosphorus and carbon composite is introduced. Based on the summary, the future development trend and potential of black phosphorus materials in the field of electrochemistry are analyzed.
Lithium (Li) metal anode has received extensive attentions due to its ultrahigh theoretical capacity and the most negative electrode potential. However, dendrite growth severely impedes the practical applications of the Li metal anode in rechargeable batteries. In this contribution, a mesoporous graphene with a high specific surface area was synthesized to host the Li metal anode. The mesoporous graphene host (MGH) has a high specific surface area (2090 m2/g), which affords free space and an interconnected conductive pathway for Li plating and stripping, thus alleviating the volume variation and reducing the generation of dead Li during repeated cycles. More importantly, the high specific surface area of MGH efficiently reduces the local current density of the electrode, which favors a uniform Li nucleation and plating behavior, rendering a dendrite-free deposition morphology at a low overpotential. These factors synergistically boost the Li utilization (90.1% vs. 70.1% for Cu foil) and life span (150 cycles vs. 100 cycles for Cu foil) with a low polarization of MGH electrode at an ultrahigh current of 15.0 mA/cm2. The as-prepared MGH can provide fresh insights into the electrode design of the Li metal anode operating at high rates.
The purpose of this work was to enhance the corrosion resistance of the passive film on 304 stainless steel (SS) by chemical modification in alkaline phosphate–molybdate solutions. The 304 SS was passivated in both phosphate and phosphate–molybdate mixed solutions to investigate the effect of molybdate on its corrosion resistance. The experimental results indicated that the passive film showed better corrosion resistance in Cl−-containing solutions after modification in phosphate–molybdate solutions than in phosphate-only solutions. Energy-dispersive spectroscopy analyses revealed that the passive film formed in phosphate–molybdate solutions contained Mo and P after modification, which is the reason for the enhanced corrosion resistance.
Lithium-ion batteries (LIBs) have been developed for over 30 years; however, existing electrode materials cannot satisfy the increasing requirements of high-energy density, stable cycling, and low cost. Here, we present a perovskite-type LaNiO3 oxide (LNO) as a new negative electrode material. LNO was successfully synthesized by a sol–gel method. The microstructure and electrochemical performance of LNO calcined at various temperatures have been systematically investigated. The LNO electrode shows a high rate capability and long cycling stability. In a C-rate test, a specific capacity of 77 mAh/g was exhibited at 6 C. LNO can also deliver a specific capacity of 92 mAh/g after 200 cycles at 1 C. This paper presents a type of binary metal oxide as a new anode material for high-performance LIBs.