Green Energy & Environment最新文献

A fundamental question in the oxygen reduction reaction (ORR) is how to rationally control the electrocatalytic selectivity for opening a four-electron reaction pathway. However, it still lacks direct experimental evidence to understand the reaction mechanism. This work unravels that Ag nanoparticles and carbonizing halloysite nanotubes (CHNTs) can trigger the construction of oxygen defects in the MnO₂, which contribute to the generation of active sites. The Ag/MnO₂-CHNTs delivers a superior activity toward ORR with high onset potential, half-wave potential, diffusion-limited current density, long-term durability and methanol tolerance. More importantly, combined with density functional theory calculations, triggering manganese dioxide defects upon the introduction of Ag nanoparticles and CHNTs can alter the electrocatalytic pathway from a two-electron to a direct four-electron direction for ORR, which is the nature of enhanced ORR activity. Based on the analysis of the results, this finding points out a very effective approach for exploring catalysts with the improved performance and durability for ORR reaction.

KVPO₄F (KVPF) has been extensively investigated as the potential cathode material for potassium-ion batteries (PIBs) owing to its high theoretical capacity, superior operating voltage, and three-dimensional K⁺ conduction pathway. Nevertheless, the electrochemical behavior of KVPF is limited by the inherent poor electronic conductivity of the phosphate framework and unstable electrode/electrolyte interface. To address the above issues, this work proposes an infiltration-calcination method to confine the in-situ grown KVPF into the mesoporous carbon CMK-3 (denoted KVPF@CMK-3). The assembled KVPF@CMK-3 nanocomposite features three-dimensional interconnected carbon channels, which not only offer abundant active sites and significantly accelerate K⁺/electron transport, but also prevent the growth of KVPF nanoparticle agglomerates, hence stabilizing the structure of the material. Additionally, V–F–C bonds are created at the interface of KVPF and CMK-3, which reduce the loss of F and stabilize the electrode interface. Thus, when tested as a cathode material for PIBs, the KVPF@CMK-3 nanocomposite delivers superior reversible capacitiy (103.2 mAh g⁻¹ at 0.2 C), outstanding rate performance (90.1 mAh g⁻¹ at 20 C), and steady cycling performance (92.2 mAh g⁻¹ at 10 C and with the retention of 88.2% after 500 cycles). Moreover, its potassium storage mechanism is further examined by ex-situ XRD and ex-situ XPS techniques. The above synthetic strategy demonstrates the potential of KVPF@CMK-3 to be applied as the cathode for PIBs.

Green energy storage devices play vital roles in reducing fossil fuel emissions and achieving carbon neutrality by 2050. Growing markets for portable electronics and electric vehicles create tremendous demand for advanced lithium-ion batteries (LIBs) with high power and energy density, and novel electrode material with high capacity and energy density is one of the keys to next-generation LIBs. Silicon-based materials, with high specific capacity, abundant natural resources, high-level safety and environmental friendliness, are quite promising alternative anode materials. However, significant volume expansion and redundant side reactions with electrolytes lead to active lithium loss and decreased coulombic efficiency (CE) of silicon-based material, which hinders the commercial application of silicon-based anode. Prelithiation, pre-embedding extra lithium ions in the electrodes, is a promising approach to replenish the lithium loss during cycling. Recent progress on prelithiation strategies for silicon-based anode, including electrochemical method, chemical method, direct contact method, and active material method, and their practical potentials are reviewed and prospected here. The development of advanced Si-based material and prelithiation technologies is expected to provide promising approaches for the large-scale application of silicon-based materials.

The component analysis and structure characterization of complex mixtures of biomass conversion remain a challenging work. Hence, developing effective and easy to use techniques is necessary. Diffusion-ordered NMR spectroscopy (DOSY) is a non-selective and non-invasive method capable of achieving pseudo-separation and structure assignments of individual compounds from biomass mixtures by providing diffusion coefficients (D) of the components. However, the conventional ¹H DOSY NMR is limited by crowded resonances when analyzing complex mixtures containing similar chemical structure resulting in similar coefficient. Herein we describe the application of an advanced diffusion NMR method, Pure Shift Yielded by CHirp Excitation DOSY (PSYCHE-iDOSY), which can record high-resolution signal diffusion spectra efficiently separating compounds in model and genuine mixture samples from cellulose, hemicellulose and lignin. Complicated sets of isomers (d-glucose/d-fructose/d-mannose and 1,2-/1,5-pentadiol), homologous compounds (ethylene glycol and 1,2-propylene glycol), model compounds of lignin, and a genuine reaction system (furfuryl alcohol hydrogenolysis with ring opening) were successfully separated in the diffusion dimension. The results show that the ultrahigh-resolution DOSY technique is capable of detecting and pseudo-separating the mixture components of C₅/C₆ sugar conversion products and its derivative hydrogenation/hydrogenolysis from lignocellulose biomass.

New energy sources that reduce the volume of harmful gases such as SO_x and NO_x released into the atmosphere are in constant development. Natural gas, primarily made up of methane, is being widely used as one reliable energy source for heating and electricity generation due to its high combustion value. Currently, natural gas accounts for a large portion of electricity generation and chemical feedstock in manufacturing plastics and other commercially important organic chemicals. In the near future, natural gas will be widely used as a fuel for vehicles. Therefore, a practical storage device for its storage and transportation is very beneficial to the deployment of natural gas as an energy source for new technologies. In this tutorial review, biomaterials-based carbon monoliths (CMs), one kind of carbonaceous material, was reviewed as an adsorbent for natural gas (methane) adsorption and storage.

Efficient and stable oxygen evolution electrocatalysts are indispensable for industrial applications of water splitting and hydrogen production. Herein, a simple and practical method was applied to fabricate (Mo, Fe)P₂O₇@NF electrocatalyst by directly growing Mo/Fe bimetallic pyrophosphate derived from Prussian blue analogues on three-dimensional porous current collector. In alkaline media, the developed material possesses good hydrophilic features and exhibits best-in-class oxygen evolution reaction (OER) performances. Surprisingly, the (Mo, Fe)P₂O₇@NF only requires overpotentials of 250 and 290 mV to deliver 100 and 600 mA cm⁻² in 1 mol L⁻¹ KOH, respectively. Furthermore, the (Mo, Fe)P₂O₇@NF shows outstanding performances in alkaline salty water and 1 mol L⁻¹ high purity KOH. A worthwhile pathway is provided to combine bimetallic pyrophosphate with commercial Ni foam to form robust electrocatalysts for stable electrocatalytic OER, which has a positive impact on both hydrogen energy application and environmental restoration.

High-entropy oxides (HEOs) are gaining prominence in the field of electrochemistry due to their distinctive structural characteristics, which give rise to their advanced stable and modifiable functional properties. This review presents fundamental preparations, incidental characterizations, and typical structures of HEOs. The prospective applications of HEOs in various electrochemical aspects of electrocatalysis and energy conversion-storage are also summarized, including recent developments and the general trend of HEO structure design in the catalysis containing oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), supercapacitors (SC), lithium-ion batteries (LIBs), solid oxide fuel cells (SOFCs), and so forth. Moreover, this review notes some apparent challenges and multiple opportunities for the use of HEOs in the wide field of energy to further guide the development of practical applications. The influence of entropy is significant, and high-entropy oxides are expected to drive the improvement of energy science and technology in the near future.