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The balance between degradability and drug release kinetics is a major challenge for the development of drug delivery systems. Here we develop hierarchically structured nanoparticles comprising multiple noncontact silica shells using an amorphous calcium carbonate template. The system could be degraded in a sequential fashion on account of the molecularly engineered multishelled structures. The hydrolysis rate of drug-containing cores is inversely correlated with the nanoparticle concentration due to the shielding effect of the hierarchical nanostructure and could be exploited to regulate the release kinetics. Specifically, multishelled nanospheres show a low drug release rate with high doses that increases steadily as the concentration decreases due to continuous degradation, thus stabilizing the local drug concentration for effective tumor therapy. Moreover, the nanoparticles could be eventually degraded completely, which may reduce their health risks. This kind of hierarchically structured silica-based nanoparticle could serve as a sustainable drug depot and provides a new avenue for tumor treatment.

Conductive hydrogels that are highly elastic, fatigue resistant and environmentally adaptive are promising materials in the fields of wearable electronics, bioelectronics and soft robotics. However, these materials are challenging to develop, especially for use in harsh environments including organic solvents and extreme temperatures. Here we report a simple method for the fabrication of highly compressible and fatigue-resistant conductive hydrogels with reinforced-concrete-type constituents and high-tortuosity interconnected cellular architecture through a self-assembly and two-stage in situ polymerization process. The obtained composites exhibit excellent mechanical compressibility with negligible residual strain at 50% strain for >104 cyclic loadings both in air and water. Due to the structure-favoured anisotropic response to tensile deformations coupled with elastic recovery, the hydrogel is endowed with sensing dimensions which allow the direction and velocity of movement on the sensor surface to be distinguished. In addition, by interpenetrating with an oleophilic polymer network, highly elastic and adaptive organohydrogels are developed with outstanding sensing performance in a wide variety of organic solvents and cryogenic temperatures. These materials may therefore be suitable for use in flexible and wearable devices in harsh environments.

Mineral-based bulk structural materials (MBSMs) are known for their long history and extensive range of usage. The inherent brittleness of minerals poses a major problem to the performance of MBSMs. To overcome this problem, design principles have been extracted from natural biominerals, in which the extraordinary mechanical performance is achieved via the hierarchical organization of minerals and organics. Nevertheless, precise and efficient fabrication of MBSMs with bioinspired hierarchical structures under mild conditions has long been a big challenge. This Perspective provides a panoramic view of an emerging fabrication strategy, matrix-directed mineralization, which imitates the in vivo growth of some biominerals. The advantages of the strategy are revealed by comparatively analyzing the conventional fabrication techniques of artificial hierarchically structured MBSMs and the biomineral growth processes. By introducing recent advances, we demonstrate that this strategy can be used to fabricate artificial MBSMs with hierarchical structures. Particular attention is paid to the mass transport and the precursors that are involved in the mineralization process. We hope this Perspective can provide some inspiring viewpoints on the importance of biomimetic mineralization in material fabrication and thereby spur the biomimetic fabrication of high-performance MBSMs.

Developing highly active and selective catalysts for the hydrogenation of nitroarenes, an environmentally benign process to produce industrially important aniline intermediates, is highly desirable...

Hydrogen production from water electrolysis in neutral-pH electrolytes can not only avoid the corrosion and safety issues and expand the catalyst option but also potentially integrate with artificial photosynthesis and bioelectrocatalysis. However, heterogeneous catalysts that can efficiently negotiate the sluggish oxygen evolution reaction (OER) in neutral solutions are considerably lacking. Herein, we report a template-assisted strategy for the synthesis of 13 kinds of tube-like nanostructured perovskite oxides (TNPOs) with markedly high Brunauer-Emmett-Teller surface areas. By systematic examination of these TNPOs, we found that the OER activity of TNPOs in neutral solution exhibits a volcano shape as a function of the covalency of transition metal-oxygen bonds. Consequently, our designed Sm-doped LaCoO

The photothermoelectric effect, directly converting light energy into electrical energy, shows promising prospects in self-powered broad-band optical detection, which can extend to various applications, such as sensing, optoelectronic communications, and wide-temperature-range measurements. However, the low photosensitivity, narrow-band response, and rapid performance degeneration under continuous illumination restrict its broad application. Herein, we propose a simple bottom-up strategy to manipulate nanowires (NWs) into a well-defined multilayer Te-Ag

Finding highly efficient hydrogen evolution reaction (HER) catalysts is pertinent to the ultimate goal of transformation into a net-zero carbon emission society. The design principles for such HER catalysts lie in the well-known structure-property relationship, which guides the synthesis procedure that creates catalyst with target properties such as catalytic activity. Here we report a general strategy to synthesize 10 kinds of single-atom-doped CoSe2-DETA (DETA = diethylenetriamine) nanobelts. By systematically analyzing these products, we demonstrate a volcano-shape correlation between HER activity and Co atomic configuration (ratio of Co-N bonds to Co-Se bonds). Specifically, Pb-CoSe2-DETA catalyst reaches current density of 10 mA cm−2 at 74 mV in acidic electrolyte (0.5 M H2SO4, pH ~0.35). This striking catalytic performance can be attributed to its optimized Co atomic configuration induced by single-atom doping.

High-performance functional fibers play a critical role in various indispensable fields, including sensing, monitoring, and display. It is desirable yet challenging to develop conductive fibers with excellent mechanical properties for practical applications. Herein, inspired by the exquisite fascicle structure of skeletal muscle, we constructed a high-performance bacterial cellulose (BC)/carbon nanotube (CNT) conductive fiber through in situ biosynthesis and enhancement of structure and interaction. The biosynthesis strategy achieves the in situ entanglement of CNTs in the three-dimensional network of BC through the deposition of CNTs during the growth of BC. The structure enhancement through physical wet drawing and the interaction enhancement through chemical treatment facilitate orientation and bridging of components, respectively. Owing to the ingenious design, the obtained composite fibers integrate high strength (939 MPa), high stiffness (52.3 GPa), high fatigue resistance, and stable electrical performance, making them competitive for constructing fiber-based smart devices for practical applications.

Picturing the atomic migration pathways of catalysts in a reactive atmosphere is of central significance for uncovering the underlying catalytic mechanisms and directing the design of high-performance catalysts. Here, we describe a reduction-controlled atomic migration pathway that converts nanoparticles to single atom alloys (SAAs), which has remained synthetically challenging in prior attempts due to the elusive mechanism. We achieved this by thermally treating the noble-metal nanoparticles M (M = Ru, Rh, Pd, Ag, Ir, Pt, and Au) on metal oxide (CuO) supports with H

Cellulose aerogels are plagued by intermolecular hydrogen bond-induced structural plasticity, otherwise rely on chemicals modification to extend service life. Here, we demonstrate a petrochemical-free strategy to fabricate superelastic cellulose aerogels by designing hierarchical structures at multi scales. Oriented channels consolidate the whole architecture. Porous walls of dehydrated cellulose derived from thermal etching not only exhibit decreased rigidity and stickiness, but also guide the microscopic deformation and mitigate localized large strain, preventing structural collapse. The aerogels show exceptional stability, including temperature-invariant elasticity, fatigue resistance (∼5 % plastic deformation after 10

The oriented pore structure of wood endows it with a variety of outstanding properties, among which the low thermal conductivity has attracted researchers to develop wood-like aerogels as excellent thermal insulation materials. However, the increasing demands of environmental protection have put forward new and strict requirements for the sustainability of aerogels. Here, we report an all-natural wood-inspired aerogel consisting of all-natural ingredients and develop a method to activate the surface-inert wood particles to construct the aerogel. The obtained wood-inspired aerogel has channel structure similar to that of natural wood, endowing it with superior thermal insulation properties to most existing commercial sponges. In addition, remarkable fire retardancy and complete biodegradability are integrated. With the above outstanding performances, this sustainable wood-inspired aerogel will be an ideal substitute for the existing commercial thermal insulation materials.

Single-atom catalysts (SACs), featuring high atom utilization, have captured widespread interests in diverse applications. However, the single-atom sites in SACs are generally recognized as independent units and the interplay of adjacent sites is largely overlooked. Herein, by the direct pyrolysis of MOFs assembled with Fe and Ni-doped ZnO nanoparticles, a novel Fe1-Ni1-N-C catalyst, with neighboring Fe and Ni single-atom pairs decorated on nitrogen-doped carbon support, has been precisely constructed. Thanks to the synergism of neighboring Fe and Ni single-atom pairs, Fe1-Ni1-N-C presents significantly boosted performances for electrocatalytic reduction of CO2, far surpassing Fe1-N-C and Ni1-N-C with separate Fe or Ni single atoms. Additionally, the Fe1-Ni1-N-C also exhibits superior performance with excellent CO selectivity and durability in Zn-CO2 battery. Theoretical simulations reveal that, in Fe1-Ni1-N-C, single Fe atoms can be highly activated by adjacent single-atom Ni via non-bonding interaction, significantly facilitating the formation of COOH* intermediate and thereby accelerating the overall CO2 reduction. This work supplies a general strategy to construct single-atom catalysts containing multiple metal species and reveals the vital importance of the communitive effect between adjacent single atoms toward improved catalysis.

Skin-mountable capacitive-type strain sensors with great linearity and low hysteresis provide inspiration for the interactions between human and machine. For practicality, high sensing performance, large stretchability, and self-healing are demanded but limited by stretchable electrode and dielectric and interfacial compatibility. Here, we demonstrate an extremely stretchable and self-healing conductor via both hard and soft tactics that combine conductive nanowire assemblies with double dynamic network based on π-π attractions and Ag-S coordination bonds. The obtained conductor outperforms the reported stretchable conductors by delivering an elongation of 3250%, resistance change of 223% at 2000% strain, high durability, and multiresponsive self-healability. Especially, this conductor accommodates large strain of 1500% at extremely knotted and twisted deformations. By sandwiching hydrogel conductors with a newly developed dielectric, ultrahigh stretchability and omni-healability are simultaneously achieved for the first time for a capacitive strain sensor inspired by metal-thiolate coordination chemistry, showing great potentials in wearable electronics and soft robotics.

Two-dimensional (2D) IV–VI nanomaterials have been important candidates for energy conversion and storage. However, there is still lack of a simple method of realizing control synthesis of IV–VI na...

Softness, adhesion, stretchability, and fast recovery from large deformations are essential properties for conductive elastomers that play an important role in the development of high-performance soft electronics. However, it remains an ongoing challenge to obtain conductive elastomers that combine these properties. We have fabricated a super soft (Young's modulus 2.3-12 kPa), highly stretchable (up to 1500% strain), and underwater adhesive silicone conductive elastomer composite (SF-C-PDMS) by incorporating dimethyl silicone oil as a lubricating agent in a cross-linked molecular network. The resultant SF-C-PDMS not only exhibits superior softness but also can readily recover after a strain of 1000%. The initial resistance only decreases by 8% after 100000 cycles of tensile fatigue test (100% strain, 0.5 Hz, 15 mm/s). This multifunctional silicone conductive elastomer composite is obtained in a one-step preparation at room temperature using commercially available materials. Moreover, we illustrate the capabilities of this composite in motion sensing.

Facilitating charge separation and transport of semiconductors is pivotal to improving their solar-to-hydrogen conversion efficiency. To this end, manipulating the charge dynamics via element doping has attracted much attentions. Here, we doped phosphorus (P) into two-dimensional (2D) single-crystalline quaternary sulfide (SCQS) nanobelts, enabling significantly enhanced photocatalytic H

Additive manufacturing (AM) is the key to creating a wide variety of 3D structures with unique and programmable functionalities. Direct ink writing is one of the widely used AM technologies with numerous printable materials. However, the extrude-based method is limited by low fabrication resolution, which is confined to printing macrostructures. Herein, a new AM strategy is reported, using a low-cost extrusion 3D printer, to create 3D microarchitectures at the macroscopic level through controlled desiccation of preprinted hydrogel scaffolds followed by infilling objective components. A printable hydrogel with a high-water content ensures maximum shrinkage (≈99.5% in volume) of the printed scaffolds to achieve high resolution. Stable covalent cross-linking and a suitable drying rate enable uniform shrinkage of the scaffolds to retain their original architectures. Particularly, this method can be adapted to produce liquid-metal-based 3D circuits and nanocomposite-based microrobots, indicating its capability to fabricate functional and complex 3D architectures with micron-level resolution from different material systems.

As the key intermediate phase of crystalline calcium carbonate biominerals, amorphous calcium carbonate (ACC) remains mysterious in its structures because of its long-range disorder and instability. We herein report the synthesis of ACC nanospheres in a water-deficient organic solvent system. The obtained ACC nanospheres are very stable under dry conditions. Cryo-TEM reveals that each nanospheres consists of smaller nanosized clusters. We further demonstrate that these clusters can precipitate on other substrates to form an ultrathin ACC coating, which should be an ACC cluster monolayer. The results demonstrate that the presence of small ACC clusters as the subunits of larger aggregates is inherent to ACC synthesized in water-alcohol system but not induced by polymer additives.

Direct and rapid printing and surface patterning of hydrogel thin films are of great significance in the construction of advanced electronic devices, yet they are greatly underdeveloped due to the intrinsic contradiction between mechanical strength and self-healability as well as recyclability. Here, we present a universal and rapid slipping-directed route with a newly developed water-soluble star polymer hydrogel for direct and reproducible printing and patterning of freestanding functional thin films with precisely controlled thicknesses, components, and surface structures on a large scale. The resulting thin films combine the features of large transmittance (93%), tough mechanical strength (114 MPa), multiresponsive self-healability, recyclability, and remarkable multifunctionality. With the unique humidity-sensitive properties as motivation, diverse humidity-sensing devices including an actuating switch, a supercapacitive sensor, and a noncontact electronic skin are facilely constructed through the humidity-induced transverse, longitudinal, and patterning assembly techniques, respectively. The method presented here is universal and efficient in the fabrication and assembly of thin films with controlled configuration and functionality for advanced flexible electronics.

Widely used disposable plastic tableware is usually buried or directly discharged into the natural environment after using, which poses potential threats to the natural environment and human health. To solve this problem, nondegradable plastic tableware needs to be replaced by tableware composed of biodegradable structural materials with both food safety and the excellent mechanical and thermal properties. Here, a food-safe sargassum cellulose nanofiber (SCNF) is extracted from common seaweed in an efficient and low energy consuming way under mild reaction conditions. Then, by assembling the SCNF into a dense bulk material, a strong sargassum cellulose nanofiber structural material (SCNSM) with high strength (283 MPa) and high thermal stability (160 °C) can be prepared. The SCNSM also possesses good machinability, which can be processed into tableware with different shapes, e.g., knives and forks. The overall performance of the SCNSM-based tableware is better than commercial plastic, wood-based, and poly(lactic acid) tableware, which shows great application potential in the tableware field.

Although short bamboo nodes function in mechanical support and fluid exchange for bamboo survival, their structures are not fully understood compared to unidirectional fibrous internodes. Here, we identify the spatial heterostructure of the bamboo node via multiscale imaging strategies and investigate its mechanical properties by multimodal mechanical tests. We find three kinds of hierarchical fiber reinforcement schemes that originate from the bamboo node, including spatially tightened interlocking, triaxial interconnected scaffolding and isotropic intertwining. These reinforcement schemes, built on porous vascular bundles, microfibers and more-refined twist-aligned nanofibers, govern the structural stability of the bamboo via hierarchical toughening. In addition, the spatial liquid transport associated with these multiscale fibers within the bamboo node is experimentally verified, which gives perceptible evidence for life-indispensable multidirectional fluid exchange. The functional integration of mechanical reinforcement and liquid transport reflects the fact that the bamboo node has opted for elaborate structural optimization rather than ingredient richness. This study will advance our understanding of biological materials and provide insight into the design of fiber-reinforced structures and biomass utilization.

Designing polytypic homojunction is an efficient way to regulate photogenerated electrons and holes, thereafter bringing desired physical and chemical properties and being attractive photocatalysts for solar-to-hydrogen conversion. However, the high-yield and controllable synthesis of well-defined polytypes especially for multinary chalcogenide - the fundamental factor favoring highly efficient solar-to-hydrogen conversion - has yet to be achieved. Here, we report a general colloidal method to construct a library of polytypic copper-based quaternary sulfide nanocrystals, including Cu2ZnSnS4, Cu2CdSnS4, Cu2CoSnS4, Cu2MnSnS4, Cu2FeSnS4, Cu3InSnS5 and Cu3GaSnS5, which can be synthesized by selective epitaxial growth of kesterite phase on wurtzite structure. Besides, this colloidal method allows the precise controlling of the homojunction number corresponding to the photocatalytic performance. The single-homojunction and double-homojunction polytypic Cu2ZnSnS4 nanocrystal photocatalysts show 2.8-fold and 3.9-fold improvement in photocatalytic hydrogen evolution rates relative to the kesterite nanocrystals, respectively. This homojunction existed in the polytypic structure opens another way to engineer photocatalysts.

Soft matter catalyst system allowing controllable manipulation of the organized nanostructure and surface property holds the potential for renewable energy. Here we demonstrate the construction of a continuously regenerative hydrogel photocatalyst that confines the metal-thiolate coordination induced nanocavity into robust micro-sized spongy network for water splitting. Thanks to low vaporization enthalpy and fast proton mobility of water molecules confining in nanocavities, the composite delivers outstanding photocatalytic H

The kinetics of electrode reactions including mass transfer and surface reaction is essential in electrocatalysis, as it strongly determines the apparent reaction rates, especially on nanostructured electrocatalysts. However, important challenges still remain in optimizing the kinetics of given catalysts with suitable constituents, morphology, and crystalline design to maximize the electrocatalytic performances. We propose a comprehensive kinetic model coupling mass transfer and surface reaction on the nanocatalyst-modified electrode surface to explore and shed light on the kinetic optimization in electrocatalysis. Moreover, a theory-guided microchemical engineering (MCE) strategy has been demonstrated to rationally redesign the catalysts with optimized kinetics. Experimental measurements for methanol oxidation reaction in a 3D ordered channel with tunable channel sizes confirm the calculation prediction. Under the optimized channel size, mass transfer and surface reaction in the channeled microreactor are both well regulated. This MCE strategy will bring about a significant leap forward in structured catalyst design and kinetic modulation.

Energy is an important substantial foundation for the survival and development of humans. However, the over-consumption of resources and environmental pollution have become more prominent. The key factors for solving energy problems are to increase energy utilization efficiency and optimize energy structure. The development of new materials is the research emphasis in the field of material chemistry all the time. For instance, developing new light-capture materials and catalysts to improve the efficiency of existing photovoltaic cells is one of the most effective approaches to increasing solar power capacity radically. The design of high-performance catalytic materials to make better use of energy from fossil fuels and biomass. In addition, it is an important research direction of material chemistry and energy chemistry to deeply understand the reaction mechanism of energy conversion.

Conductive and adhesive hydrogels are promising materials for designing bioelectronics. To satisfy the high conductivity of bioelectronic devices, metal nanomaterials have been used to fabricate composite hydrogels. However, the fabrication of a conductive-nanomaterial-incorporated hydrogel with high performance is a great challenge because of the easy aggregation nature of conductive nanomaterials making processing difficult. Here, we report a kind of adhesive aero-hydrogel hybrid conductor (AAHC) with stretchable, adhesive and anti-bacteria properties by in situ formation of a hydrogel network in the aerogel-silver nanowires (AgNWs) assembly. The AgNWs with good conductivity are well-integrated on the inner-surface of shape-memory chitosan aerogel, which created a conductive framework to allow hydrogel back-filling. Reinforcement by the aerogel-silver makes the hybrid hydrogel tough and stretchable. Functional groups from the hydrogel allow strong adhesion to wet tissues through molecular stitches. The inherent bacteria-killing ability of silver ions endows the conductive hydrogel with excellent anti-bacteria performance. The proposed facile strategy of aerogel-assisted assembly of metal nanomaterials with hydrogel opens a new route to incorporate functional nanoscale building blocks into hydrogels.

Compared with raw rectorite microplatelets (RMs), rectorite nanosheets (RNs) have considerably greater application prospects in the preparation of advanced composite materials because of their larger aspect ratio, higher surface reactivity, and intrinsically superior mechanical and physical properties. However, the difficulty in the efficient preparation of RNs significantly limits their large-scale applications. Here, a scalable poly(vinylpyrrolidone)-assisted stirring approach is developed to prepare ultrathin RNs from the abundant natural RMs. A higher production rate (≈0.675 g h