The microbubble and microinterface play key roles in the development and progress of the technology in the field of chemical engineering, which has attracted broad attention from the scientific and industrial community. Recently, Zhang et al. published a book about microinterfacial mass transfer intensification technology, where they systematically introduced scientific essence, reaction mechanism, equipment structure, and influence law of multiphase reaction process strengthened by microinterface. I believe this book can promote the technological innovation of microbubble-related processes, and also the development of the green chemical industry!

Sodium-ion batteries are very promising in large-scale energy storage. The exploration of Na layered oxides as cathode materials for Na ion batteries usually consumes much resource, while the performances of Na layered oxides are dominated by their crystal structures. Therefore, it is highly desired to predict the stacking mode of the target oxides in advance: whether O3-type with higher ordered structure and stability, or P2-type with more Na content. For this purpose density functional theory computations do not work. Very recently, Hu's group and international collaborators have proposed a cationic potential to provide a very timely, effective, and accurate criterion to predict the stacking mode of Na layered oxides (Science, 370 (2020) 708–711). Under the guidance of the cationic potential phase map, Na layered oxides could be rationally designed. Here we would like to highlight the progress that novel Na layered oxides could be obtained with the combination of large specific capacity, high power density and good cycling stability.

Hydrogen production by water electrolysis is a compelling technology to produce fuels and chemicals powered by renewable energy. It is highly desirable to develop cost-effective and durable electrocatalysts for hydrogen evolution reaction (HER). This review has summarized recent progress in mechanism understanding of non-precious metal electrocatalysts for pH-universal HER. The general approaches have been demonstrated to overcome the activity/stability limitations of the electrocatalysts for HER in a broad pH range. The perspectives and challenges for the development of pH-universal HER electrocatalysts have also been proposed. This review sheds light on the design and fabrication of high-performance electrocatalysts for versatile HER-related energy technologies.

Photoelectrochemical (PEC) water splitting is considered as an ideal technology to produce hydrogen. Photogenerated carrier migration is one of the most important roles in the whole process of PEC water splitting. It includes bulk transfer inside of the photoelectrode and the exchange at the solid–liquid interface. The energy barriers during the migration process lead to the dramatic recombination of photogenerated hot carrier and the reducing of their redox capacity. Thus, an applied bias voltage should be provided to overcome these energy barriers, which brings the additional loss of energy. Plentiful researches indicate that some methods for the regulation of photogenerated hot carrier, such as p-n junction, unique transfer nanochannel, tandem nanostructure and Z-Scheme transfer structure et al., show great potential to achieve high-efficient PEC water overall splitting without any applied bias voltage. Up to now, many reviews have summarized and analyzed the methods to enhance the PEC or photocatalysis water splitting from the perspectives of materials, nanostructures and surface modification etc. However, few of them focus on the topic of photogenerated carrier transfer regulation, which is an important and urgent developing technique. For this reason, this review focuses on the regulation of photogenerated carriers generated by the photoelectrodes and summarizes different advanced methods for photogenerated carrier regulation developed in recent years. Some comments and outlooks are also provided at the end of this review.

The synthesis of low-cost and highly active electrodes for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is very important for water splitting. In this work, the novel amorphous iron-nickel phosphide (FeP-Ni) nanocone arrays as efficient bifunctional electrodes for overall water splitting have been in-situ assembled on conductive three-dimensional (3D) Ni foam via a facile and mild liquid deposition process. It is found that the FeP-Ni electrode demonstrates highly efficient electrocatalytic performance toward overall water splitting. In 1 M KOH electrolyte, the optimal FeP-Ni electrode drives a current density of 10 mA cm^-2 at overpotential of 218 mV for the OER and 120 mV for the HER, and can attain such current density for 25 h without performance regression. Moreover, a two-electrode electrolyzer comprising the FeP-Ni electrodes can afford 10 mA cm^-2 electrolysis current at a low cell voltage of 1.62 V and maintain long-term stability, as well as superior to that of the coupled RuO₂/NF‖Pt/C/NF cell. Detailed characterizations confirm that the excellent electrocatalytic performances for water splitting are attributed to the unique 3D morphology of nanocone arrays, which could expose more surface active sites, facilitate electrolyte diffusion, and benefit charge transfer and also favorable bubble detachment behavior. Our work presents a facile and cost-effective pathway to design and develop active self-supported electrodes with novel 3D morphology for water electrolysis.

Serious shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPSs) have a massive impact on obstructing the practical application of lithium-sulfur (Li–S) batteries. To address such issues, Fe-Nx sites enriched microporous nanoflowers planted with tangled bamboo-like carbon nanotubes (Fe-Nx-C/Fe₃C-CNTs NFs) are found to be effective catalytic mediators with strong anchoring capabilities for LiPSs. The bamboo-like carbon nanotubes catalyzed by Fe₃C/Fe entangled each other to form a conductive network, which encloses a flower-like microporous carbon core with embedded well-dispersed Fe-Nx active sites. As expected, electrons smoothly transfer along the dense conductive bamboo-like carbon network while the flower-like carbon core consisting of micropores induces the homogeneous distribution of tiny sulfur and favors the lithium ions migration with all directions. Meanwhile, Fe-Nx sites strongly trap long-chain LiPSs with chemical anchoring, and catalyze the redox conversion of LiPSs. Due to the aforementioned synergistic effects, the S@Fe-Nx-C/Fe₃C-CNTs NFs cathode exhibited a remarkable specific capacity (635 mAh ${\rm{g}}_{\rm{s}}^{{\rm{ - 1}}}$) at 3 C and a favorable capacity decay with 0.04% per cycle even after 400 cycles at 1 C.

Among the many strategies to fabricate the silicon/carbon composite, yolk/double-shells structure can be regarded as an effective strategy to overcome the intrinsic defects of Si-based anode materials for Li-ion batteries (LIBs). Hereon, a facile and inexpensive technology to prepare silicon/carbon composite with yolk/double-shells structure is proposed, in which the double buffering carbon shells are fabricated. The silicon/carbon nanoparticles with core–shell structure are encapsulated by SiO₂ and external carbon layer, and it shows the yolk/double-shells structure via etching the SiO₂ sacrificial layer. The multiply shells structure not only significantly improves the electrical conductivity of composite, but also effectively prevents the exposure of Si particles from the electrolyte composition. Meanwhile, the yolk/double-shells structure can provide enough space to accommodate the volume change of the electrode during charge/discharge process and avoid the pulverization of Si particles. Moreover, the as–prepared YDS-Si/C shows excellent performance as anode of LIBs, the reversible capacity is as high as 1066 mA h g^-1 at the current density of 0.5 A g^-1 after 200 cycles. At the same time, the YDS-Si/C has high capacity retention and good cyclic stability. Therefore, the unique architecture design of yolk/double-shells for Si/C composite provides an instructive exploration for the development of next generation anode materials of LIBs with high electrochemical performances and structural stability.

Hydrogen can serve as a carrier to store renewable energy in large scale. However, hydrogen storage still remains a challenge in the current stage. It is difficult to meet the technical requirements applying the conventional storage of compressed gaseous hydrogen in high-pressure tanks or the solid-state storage of hydrogen in suitable materials. In the present work, a gaseous and solid-state (G-S) hybrid hydrogen storage system with a low working pressure below 5 MPa for a 10 kW hydrogen energy storage experiment platform is developed and validated. A Ti–Mn type hydrogen storage alloy with an effective hydrogen capacity of 1.7 wt% was prepared for the G-S hybrid hydrogen storage system. The G-S hybrid hydrogen storage tank has a high volumetric hydrogen storage density of 40.07 kg H₂ m^-3 and stores hydrogen under pressure below 5 MPa. It can readily release enough hydrogen at a temperature as low as -15 ℃ when the FC system is not fully activated and hot water is not available. The energy storage efficiency of this G-S hybrid hydrogen storage system is calculated to be 86.4%–95.9% when it is combined with an FC system. This work provides a method on how to design a G-S hydrogen storage system based on practical demands and demonstrates that the G-S hybrid hydrogen storage is a promising method for stationary hydrogen storage application.

Reducing nitrogen to ammonia with solar energy has become a wide concern when it comes to photocatalysis research. It is considered to be one of the more promising alternate options for the conventional Haber–Bosch cycle. Herein, 2D g-C₃N₄ composites with modifying ultrathin sheet MnO_2-x were prepared and used as nitrogen fixation photocatalyst. With the assistance of the nature of MnO_2-x, the generation rate of NH₃ reached 225 μmol g^-1 h^-1, which is more than twice over the rate of pristine 2D g-C₃N₄ (107 μmol g^-1 h^-1). The presence of ultrathin sheet MnO_2-x shortens the gap of the carriers to the surface of photocatalyst. Thus the speed of electron transfer gets increased. Besides, the construction of Z-scheme heterojunction boosts the separation and migration of photogenerated carriers. As a result, the nitrogen reduction reaction (NRR) performance gets enhanced. The work may provide an example of promoting the NRR performance of non-metallic compound.

Catalytic hydrogenation of furfural to furfuryl alcohol is an important upgrading process for valorization of biomass-derived furanyl platform molecules. However, selective hydrogenation of α,β-unsaturated aldehydes like furfural to the corresponding alcohols at ambient pressure remains challenging in sustainable chemistry. Till date heterogeneous Au hydrogenation catalyst has been scarcely reported for this reaction due to the low reactivity of Au for H₂ dissociation. In this work, we showed that Au nanoparticles (loading: 0.2 wt%) with a mean size of about 3 nm supported on Cu-doped Al₂O₃ can efficiently hydrogenate furfural to furfuryl alcohol in liquid phase at ambient pressure. We demonstrated that doping a small amount of Cu (2 mol%) to γ-Al₂O₃ may modify the Lewis acidity-basicity of Al₂O₃ and simultaneously induce the presence of sufficient Cu⁺ species on surface, which facilitated the hydrogen transfer from i-PrOH to furfural. Moreover, we observed an enhanced reactivity of Au toward molecular H₂ via cooperation with the Lewis acidic-basic Cu₂O-Al₂O₃ support. Hence, 100% yield to furfuryl alcohol with a productivity of 0.98 g_FA·h^-1·${\rm{g}}_{{\rm{cat}}}^{{\rm{ - 1}}}$ at 120 ℃ and 0.1 MPa H₂ can be obtained. The prepared Au/Cu-Al₂O₃ catalyst was found reusable and was effective to the concentrated furfural solution, as well as several typical unsaturated aldehydes.

Oxides with different crystal phases can have important effects on the configuration of surface atoms, which can further affect the distribution of hydrogenation sites and acidic sites as well as the competitions of these varied types of catalytic sites. This could be potentially used to tailor the distribution of the products. In this study, zirconium oxides with different crystal phases supported copper catalysts were prepared for the hydrogenation of the biomass-derived furfural, vanillin, etc. The results showed that both calcination temperature and Cu species affected the shift of zirconia from tetragonal phase to the monoclinic phase. Monoclinic zirconia supported copper catalyst can effectively catalyze the hydrogenation of furfural to furfuryl alcohol via hydrogenation route due to its low amount of Brønsted acidic sites, although the surface area and the exposed metallic Cu surface area were much lower than the tetragonal zirconia supported copper catalyst. Zirconia with tetragonal or tetragonal/monoclinic phases supported copper catalysts contain abundant acidic sites and especially the Brønsted acidic sites, which catalyzed mainly the conversion of furfural via the acid-catalyzed routes such as the acetalization, rather than the hydrogenation. The acidic sites over the Cu/ZrO₂ catalyst played more predominant roles than the hydrogenation sites in determining the conversion of the organics like furfural and vanillin.

Developing a highly active and durable non-noble metal catalyst for aqueous-phase levulinic acid (LA) hydrogenation to γ-valerolactone (GVL) is an appealing yet challenging task. Herein, we report well-dispersed Co nanoparticles (NPs) embedded in nitrogen-doped mesoporous carbon nanofibers as an efficient catalyst for aqueous-phase LA hydrogenation to GVL. The Co zeolitic imidazolate framework (ZIF-67) nanocrystals were anchored on the sodium dodecyl sulfate modified wipe fiber (WF-S), yielding one-dimensional (1-D) structured composite (ZIF-67/WF-S). Subsequently, Co NPs were uniformly embedded in nitrogen-doped mesoporous carbon nanofibers (Co^RNC/SMCNF) through a pyrolysis-reduction strategy using ZIF-67/WF-S as the precursor. Benefiting from introducing modified wipe fiber WF-S to enhance the dispersion of Co NPs, and Co⁰ with Co-N_x dual active sites, the resulting Co^RNC/SMCNF catalyst shows brilliant catalytic activity (206 h^-1 turnover frequency). Additionally, the strong metal–support interactions greatly inhibited the Co NPs from aggregation and leaching from the mesoporous carbon nanofibers, and thus increasing the reusability of the Co^RNC/SMCNF catalyst (reusable nine times without notable activity loss).

Recyclable polymers offer a great opportunity to address the environmental issues of plastics. Herein, functionalization of recyclable polymers, poly ((R)-3,4-trans six-membered ring-fused GBL) (P ((R)-   M  )), were reported via end-group modifications and block/random copolymerizations. Di-n-butylmagnesium was selected to catalyze ring-opening polymerization (ROP) of (R)-   M   in the presence of a series of functional alcohols as the initiators. Block/random copolymerizations of (R)-   M   and ε-caprolactone (ε-CL), L-lactide (L-LA) and trimethylene carbonate (TMC) were performed to control the onset decomposition temperature (T_d), melting temperature (T_m) and glass transition temperature (T_g). These functionalized recyclable polymers would find broad applications as the sustainable plastics.

In this study, cellulose nanofibrils (CNF) of high charge (H-P-CNF) and screened size (H-P-CNF-S) were fabricated by increasing the charge of phosphorylated cellulose nanofibrils (P-CNFs) during the pre-treatment step of CNF production. Results show that the H-P-CNF have a significantly higher charge (3.41 mmol g^-1) compared with P-CNF (1.86 mmol g^-1). Centrifugation of H-P-CNF gave a supernatant with higher charge (5.4 mmol g^-1) and a reduced size (H-P-CNF-S). These tailored nanocelluloses were added to polyvinyl alcohol (PVA) solutions and the suspensions were successfully coated on porous polysulfone (PSf) supports to produce thin-film nanocomposite membranes. The humid mixed gas permeation tests show that CO₂ permeability increases for membranes with the addition of H-P-CNF-S by 52% and 160%, compared with the P-CNF/PVA membrane and neat PVA membrane, respectively.

The reactive adsorption behavior of thiophene on the reduced Ni/ZnO sample was investigated by a combination of theoretical and experimental study. It is widely accepted that Ni is responsible for the sulfur-removal of thiophene to release S-free hydrocarbons. Such surface reaction was simulated by DFT method. It is demonstrated that thiophene is mainly adsorbed as π-complexation mode over metallic Ni. During desulfurization, the Ssingle bondNi bond is formed and the Csingle bondS bond is thus split without pre-hydrogenation, resulting in the formation of Ni₃S₂ phase and S-free C4 olefin which can be further saturated in the presence of H₂. The S-transfer between Ni₃S₂ and ZnO was monitored by in-situ XRD and STEM with EDS mapping. Two essential features were identified for efficient S-transfer, namely, 1) the H₂ atmosphere, and 2) the two phases are presented with close contact. Based on the acquired information, a general scenario of sulfur trail has been proposed for the desulfurization of thiophene on Ni/ZnO.

Lithium (Li) is an important energy metal in the 21st century. However, the selective recovery of Li is still a big challenge, especially from acidic solutions with multiple metal ions existence. Herein we report a new ion pair induced mechanism for selectively extracting Li⁺ from acidic chloride solutions by tributyl phosphate (TBP). It is shown that the acidity and the chloride ions in the aqueous phase have great effects on the extraction of Li⁺. The FT-IR, UV-Vis and ESI-MS experiments provide solid evidence for the formation of ion-pair complex [Li(TBP)_n(H₂O)_m]⁺[FeCl₄]^- (n = 1, 2, 3; m = 0, 1) in the organic phase, which brings about the effective and efficient extraction of Li⁺. This mechanism can overcome the Hofmeister bias and allow for the selective extraction of Li⁺ from the extremely hydrophilic chlorides. It has also been proved that the loaded Li in TBP can be effectively stripped by concentrated HCl solution with a Li/Fe separation factor > 500. The understanding of the ion-pair transport mechanism is helpful for optimizing the recovery process or further advancing more efficient recovery techniques for Li from acidic liquor.