Metal–organic frameworks (MOFs) are a class of versatile porous crystalline materials with great potential for a variety of applications. MOF@MOF composites, through heterogeneous structural design, can combine the complementary properties of different MOFs and break through the limitations of single-phase MOFs with marked synergistic effects and enhanced functional properties. This review provides a timely and comprehensive analysis of MOF@MOF composite research. First, we systematically outline the synthetic methodologies. Next, we clarify the fundamental interactions between host and guest frameworks. Subsequently, the variety of MOF@MOF composites is analyzed to show how their hybrid configurations facilitate innovation across diverse applications. The discussion then shifts to specific practical uses of these composite materials. Finally, the article highlights the challenges and future directions in the development of MOF@MOF composites, offering insights into opportunities for continued exploration and optimization.

The removal of persistent organic pollutants through catalytic ozonation remains a significant challenge, particularly in developing catalysts that combine high efficiency with robust stability. To address this, we present an innovative strategy for synthesizing a series of energetic metal-organic framework (EMOF)-derived porous carbon spheres doped with various transition metals (denoted as EMS, EMFeS, EMCuS, EMNiS, and EMMnS). This approach combines a phase transfer pathway with controlled expansion of energy-containing MOFs during high-temperature pyrolysis, resulting in hierarchically porous structures. When applied to tetracycline (TTCH) degradation, EMFeS exhibited remarkable catalytic activity with ozone and the reaction rate constant is 0.131 min⁻¹, which is superior to individual ozone system (0.088 min⁻¹). The superior catalytic performance is attributed to two aspects: (i) The three-dimensional hierarchical porous architecture facilitates efficient mass transfer and improves reaction kinetics, while (ii) the well-dispersed metal active sites (including Mn, Fe, Cu, and Ni) significantly enhance ozonolysis efficiency. Comprehensive mechanistic studies through quenching experiments and LC-MS analysis elucidated the degradation pathways, while continuous flow catalytic tests and biotoxicity assessments confirmed the practical applicability of these catalysts. This work not only advances the development of high-performance ozonation catalysts but also provides new insights into the design of water treatment materials.

Two-dimensional conjugated metal–organic framework (2D c-MOF) nanosheets have garnered significant research interest owing to their suite of distinctive properties. Consequently, diverse synthetic methodologies have been established for the fabrication of 2D c-MOFs exhibiting well-defined nanosheet morphology. In addition, the structural engineering of 2D c-MOF nanosheets for energy storage and conversion has emerged as a prominent research focus. This review comprehensively summarizes recent advancements in 2D c-MOF nanosheets. We commence with a concise overview of diverse synthesis strategies for these materials. Subsequently, progress in their utilization as electrode materials or catalysts for batteries, supercapacitors, and electrocatalysis/photocatalysis is systematically examined. Finally, prevailing challenges and prospective research directions are discussed. Collectively, this review aims to stimulate the development of sophisticated 2D c-MOF nanosheets for high-performance energy applications.

Machine learning (ML) is transforming material research and development (R&D), driving a fundamental shift from experience-driven approaches to data-driven frameworks. This review systematically highlights the transformative breakthroughs brought by machine learning throughout the entire process of intelligent material innovation. And it provides a comprehensive full chain analysis, from atomic scale design to macroscopic applications, emphasizing multi-scale modeling that combines physical mechanisms with data-driven methods, running through all stages of material innovation. In the design phase, ML promotes performance-oriented structural optimization through inverse design systems and generative models. For synthesis and processing, closed-loop autonomous systems and green controllable synthesis strategies significantly improve efficiency and sustainability. In terms of advanced representation, ML-powered techniques can help proactively tackle key challenges of complex structures. Performance prediction models enable precise correlations between material properties and extreme properties (such as auxiliary structures) by revealing catalytic descriptors and decoding biological interface mechanisms. Ultimately, these ML-driven advancements are unlocking practical applications in key fields, such as energy, biomedicine, environmental remediation, and structural engineering. This article aims to provide a comprehensive technological roadmap for the next generation of smart material development by integrating cross scale insights and autonomous strategies, and to outline future directions for this rapidly developing paradigm.

Metal-organic framework (MOF)-derived porous carbon has garnered extensive interest. However, MOFs will shrink inward during carbonization, which will limit the structural diversity and potential for application. In this work, a general synthesis strategy was reported. Various MOF@mSiO₂ core–shell composites were synthesized by in-situ growth, utilizing MOFs as precursors. Further, hollow mesoporous carbon was prepared after calcination by the outward contraction effect induced by compact silica coating. Furthermore, the incorporation of metal heteroatoms can also significantly enhance electrochemical performance due to the synergistic influences of bimetallic atoms. The synthesized Fe-Zn-N-MC-600 MOF-derived carbon material achieved 453 F·g⁻¹ at 0.5 A·g⁻¹ and an outstanding capacity retention rate (97% after 5000 cycles at 5 A·g⁻¹). In addition, the prepared Fe-Zn-N-MC-600//AC asymmetric supercapacitors achieved 375 F·g⁻¹ at 5 A·g⁻¹. Our task opens a universal path for MOF-derived carbon, offering new possibilities in supercapacitor technology.

Pristine tin (Sn) and tin dioxide (SnO₂) have sparked wide interest owing to their abundant resources and superior theoretical capacity. Nevertheless, the obvious volume expansion effect upon cycling and undesirable conductivity of Sn-based materials lead to undesirable specific capacity. In this work, a nanostructured Sn/SnO₂/nitrogen-doped carbon (NC) superstructure was prepared through a facile electrospray-carbonization strategy. The Sn/SnO₂ nanoparticles (NPs) were uniformly dispersed in a spherical NC matrix, which prevented the volume expansion and aggregation of NPs and facilitated the ion diffusion and charge transfer kinetics. When the optimized Sn/SnO₂/NC superstructures were employed as lithium-ion battery anodes, a remarkable specific capacity of 747.9 mAh·g⁻¹ over 200 cycles at 0.5 A·g⁻¹ and a superior cyclability of 644.1 mAh·g⁻¹ over 1000 cycles at 2 A·g⁻¹ were obtained. This effective synthetic strategy for synthesizing superstructures provides valuable insights for the advancement of lithium-ion batteries.

With the exhaustion of conventional fossil fuels, the exploration of green and sustainable energy will become an important topic of social development. Hydrogen is considered a clean and effective energy source, and its combustion produces only water, which is harmless to the environment. Photocatalytic water splitting, which utilizes solar energy and produces H₂ and O₂, can become a very important reaction for alleviating energy shortages and environmental pollution. Water splitting includes the reduction and oxidation half-reactions, among which the oxidation half-reaction is the rate-determining process. Even though current studies mainly focus on the H₂ or O₂ evolution reactions in the presence of sacrificial agents, overall water splitting remains a challenging problem. Metal–organic frameworks (MOFs) and their precursors have been attracting increasing attention as photocatalysts for water splitting. This paper reviews the research progress in MOFs for photocatalytic overall water splitting and discusses the development prospects and challenges of MOFs. In this study, the research progress in MOF-based water-splitting catalysts for photocatalysis and electrocatalysis is systematically reviewed. Herein, MOF-based catalysts are classified into MOFs, MOF composites, and MOF-derived photocatalysts. We also analyze the prospects and challenges in the preparation of efficient and stable MOF photocatalysts for overall water splitting and propose the construction of new efficient MOFs with double active sites, aiming to improve the efficiency of photocatalytic hydrogen and oxygen evolution to achieve the overall water splitting.

Uncontrollable dendrite growth and side reactions resulting in short operating life and low Coulombic efficiency have severely hindered the further development of aqueous zinc-ion batteries (AZIBs). In this work, we designed to grow zeolitic imidazolate framework-8 (ZIF-8) uniformly on CuO nanosheets (NSs) and prepared carbon-coated CuZn alloy NSs (CuZn@C NSs) by calcination under H₂/Ar atmosphere. As reflected by extended X-ray absorption fine structure (EXAFS), density functional theory (DFT), and in-situ Raman, the Cu–Zn and Zn–N bonds present in CuZn@C NSs act as zincophilic sites to uniformly absorb Zn ions and inhibit the formation of Zn dendrites. At the same time, CuZn@C NSs hinder the direct contact between zinc anode and electrolyte, preventing the occurrence of side reactions. More impressively, the symmetric cells constructed with CuZn@C NSs anodes exhibited excellent zinc plating/exfoliation performance and long life cycle at different current densities with low voltage hysteresis. In addition, low polarization, high capacity retention, and long cycle life over 1000 cycles at 5 A∙g⁻¹ were achieved when CuZn@C NSs were used as anodes for CuZn@C/V₂O₅ full cells.

Although metal–organic frameworks have been heavily tested as the anode materials for lithium-ion batteries (LIBs), the poorer conductivity, easy collapse of frameworks, and serious volume expansion limit their further application in LIBs. Herein, we report a facile approach to obtain MXene-encapsulated porous Ni-naphthalene dicarboxylic acid (Ni-NDC) nanosheets by hybridizing ultrathin Ti₃C₂ MXene and three-dimensional (3D) Ni-NDC nanosheet aggregates. In the structure of Ni-NDC/MXene hybrids, the interlayer hydrogen-bond interaction between Ni-NDC and MXene can effectively increase the interlayer spacing and further inhibit the oxidation of pure MXene. Hence, the introduction of MXene (a conductive matrix) could further improve the conductivity of Ni-NDC, avoid self-agglomeration, and buffer the volume expansion of Ni-NDC nanosheets. Benefiting from the synergistic effects between Ni-NDC and MXene, Ni-NDC/MXene hybrid electrode exhibits a reversible discharge capacity (579.8 mA∙h∙g⁻¹ at 100 mA∙g⁻¹ after 100 cycles) and good long-term cycling performance (310 mA∙h∙g⁻¹ at 1 A∙g⁻¹ after 500 cycles).

Lithium-sulfur batteries (LSBs) are considered promising new energy storage systems given their outstanding theoretical energy densities. Nevertheless, issues such as low electrical conductivity and severe volume expansion, along with the formation of polysulfides during cycling, restrict their practical applications. To overcome these issues, it is necessary to find suitable and effective sulfur host materials. Metal–organic frameworks (MOFs), which are porous crystalline materials in the bourgeoning developmental stages, have demonstrated enormous potential in LSBs owing to their high porosity and tunable porous structure. Herein, we provide a comprehensive overview of MOF-based sulfur-loaded materials and discuss the charge/discharge mechanisms, strategies of enhancing battery performance, sulfur loading methods, and applications in LSBs. An outlook on future directions, prospects, and possible obstacles for the development of these materials is also provided.