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Recently, two-dimensional transition metal dichalcogenides (2D TMDCs) have drawn certain attentions in many fields. The unique and diversified electronic structure and ultrathin sheet structure of 2D TMDCs offer opportunities for moving ahead of other 2D nanomaterials such as graphene and expanding the wide application of inorganic 2D nanomaterials in many fields. For a better understanding of 2D TMDCs, one needs to know methods for their synthesis and modification, as well as their potential applications and possible biological toxicity. Herein, we summarized the recent research progress of 2D TMDCs with particular focus on their biomedical applications and potential health risks. Firstly, two kinds of synthesis methods of 2D TMDCs, top-down and bottom-up, and methods for their surface functionalization are reviewed. Secondly, the applications of 2D TMDCs in the field of biomedicine, including drug loading, photothermal therapy, biological imaging and biosensor were summarized. After that, we presented the existing researches on biosafety evaluation of 2D TMDCs. At last, we discussed major research gap in current researches and challenges and coping strategies in future studies.

Efficient electrocatalysts for hydrogen evolution reaction are key to realize clean hydrogen production through water splitting. As an important family of functional materials, transition metal oxides are generally believed inactive towards hydrogen evolution reaction, although many of them show high activity for oxygen evolution reaction. Here we report the remarkable electrocatalytic activity for hydrogen evolution reaction of a layered metal oxide, Ruddlesden−Popper-type Sr 2 RuO 4 with alternative perovskite layer and rock-salt SrO layer, in an alkaline solution, which is comparable to those of the best electrocatalysts ever reported. By theoretical calculations, such excellent activity is attributed mainly to an unusual synergistic effect in the layered structure, whereby the (001) SrO-terminated surface cleaved in rock-salt layer facilitates a barrier-free water dissociation while the active apical oxygen site in perovskite layer promotes favorable hydrogen adsorption and evolution. Moreover, the activity of such layered oxide can be further improved by electrochemistry-induced activation. Water may serve as a renewable hydrogen fuel source to replace fossil fuels, although such electrolysis requires highly active catalysts. Here, authors explore Ruddlesden−Popper oxides as hydrogen evolution electrocatalysts that feature an unusual synergistic effect to promote high activity.

Crystalline perovskite oxides are regarded as promising electrocatalysts for water electrolysis, particularly for anodic oxygen evolution reactions, owing to their low cost and high intrinsic activity. Perovskite oxides with noncrystalline or amorphous characteristics also exhibit promising electrocatalytic performance toward electrochemical water splitting. In this review, a fundamental understanding of the characteristics and advantages of crystalline, noncrystalline, and amorphous perovskite oxides is presented. Subsequently, recent progress in the development of advanced electrocatalysts for water electrolysis by engineering and breaking the crystallinity of perovskite oxides is reviewed, with a special focus on the underlying structure–activity relationships. Finally, the remaining challenges and unsolved issues are presented, and an outlook is briefly proposed for the future exploration of next‐generation water‐splitting electrocatalysts based on perovskite oxides. This review discusses the characteristics and advantages of crystalline, noncrystalline, and amorphous perovskite oxides as highly promising electrocatalysts for water electrolysis. It summarizes recent advancements in engineering aimed at manipulating the crystallinity of perovskite oxides to enhance electrocatalytic performance. Additionally, the review addresses current challenges and proposes future research directions for developing next‐generation water‐splitting electrocatalysts based on perovskite oxides.

Reversible proton ceramic electrochemical cells are promising solid-state ion devices for efficient power generation and energy storage, but necessitate effective air electrodes to accelerate the commercial application. Here, we construct a triple-conducting hybrid electrode through a stoichiometry tuning strategy, composed of a cubic phase Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ and a hexagonal phase Ba 4 Sr 4 (Co 0.8 Fe 0.2 ) 4 O 16−δ . Unlike the common method of creating self-assembled hybrids by breaking through material tolerance limits, the strategy of adjusting the stoichiometric ratio of the A-site/B-site not only achieves strong interactions between hybrid phases, but also can efficiently modifies the phase contents. When operate as an air electrode for reversible proton ceramic electrochemical cell, the hybrid electrode with unique dual-phase synergy shows excellent electrochemical performance with a current density of 3.73 A cm −2 @ 1.3 V in electrolysis mode and a peak power density of 1.99 W cm −2 in fuel cell mode at 650 °C. Efficient air electrodes drive reversible proton ceramic electrochemical cells, accelerating renewable energy conversion and storage. Here, the authors propose a highly active hybrid air electrode that effectively controls phase content, enhancing electrochemical activity and stability through synergistic effects.

Proton exchange membrane (PEM) water electrolysis represents one of the most promising technologies to achieve green hydrogen production, but currently its practical viability is largely affected by the slow reaction kinetics of the anodic oxygen evolution reaction (OER) in an acidic environment. While noble metal‐based catalysts containing iridium or ruthenium are excellent catalysts for the acidic OER, their practical use in PEM electrolyzers is hindered due to their low abundance and high cost. Most recently, metal–organic frameworks (MOFs) have been demonstrated as a perfect platform to facilitate the design of acidic OER catalysts with both high efficiency and cost‐effectiveness. Here, we provide a timely and comprehensive overview of the recent progress on MOF‐based acidic OER catalysts. The fundamental mechanisms of the acidic OER are first introduced, followed by a summary of the development of pristine MOFs and MOF derivatives as acidic OER catalysts. Importantly, a number of catalyst design strategies are discussed aiming at improving the acidic OER catalytic performance of MOF‐based candidates. The integration of MOF‐based catalysts into real PEM water electrolyzers is also included. Finally, future research directions are provided to achieve better MOF‐based catalysts operational in acidic environments and PEM devices. Metal‐organic frameworks (MOFs) are emerging as a perfect platform to facilitate the design of acidic oxygen evolution reaction (OER) electrocatalysts to be used in proton exchange membrane (PEM) water electrolysis for green hydrogen production. This review provides a timely and comprehensive overview of the recent progress on the acidic OER catalyzed by MOF‐based materials, including both pristine MOFs and their derivatives. Catalyst design strategies are highlighted and future research directions are proposed to achieve better MOF‐based catalysts operational in acidic environments and PEM devices.

Electrochemical water splitting represents a promising technology for green hydrogen production. To design advanced electrocatalysts, it is crucial to identify their active sites and interpret the relationship between their structures and performance. Materials extensively studied as electrocatalysts include noble‐metal‐based (e.g., Ru, Ir, and Pt) and non‐noble‐metal‐based (e.g., 3d transition metals) compounds. Recently, advancements in characterization techniques and theoretical calculations have revealed novel and unusual active sites. The present review highlights the latest achievements in the discovery and identification of various unconventional active sites for electrochemical water splitting, with a focus on state‐of‐the‐art strategies for determining true active sites and establishing structure–activity relationships. Furthermore, we discuss the remaining challenges and future perspectives for the development of next‐generation electrocatalysts with unusual active sites. By presenting a fresh perspective on the unconventional reaction sites involved in electrochemical water splitting, this review aims to provide valuable guidance for the future study of electrocatalysts in industrial applications. Recent progress in characterization techniques and theoretical calculations has revealed the existence of novel and unusual active sites. This review highlights the most recent breakthroughs in the identification of diverse nontraditional active sites used for electrochemical water splitting. We emphasize cutting‐edge approaches to discern authentic active sites and establish correlations between their structures and activities.

Surface reconstruction engineering is an effective strategy to promote the catalytic activities of electrocatalysts, especially for water oxidation. Taking advantage of the physicochemical properties of precatalysts by manipulating their structural self-reconstruction levels provide a promising methodology for achieving suitable catalysts. In this review, we focus on recent advances in research related to the rational control of the process and level of surface transformation ultimately to design advanced oxygen evolution electrocatalysts. We start by discussing the original contributions to surface changes during electrochemical reactions and related factors that can influence the electrocatalytic properties of materials. We then present an overview of current developments and a summary of recently proposed strategies to boost electrochemical performance outcomes by the controlling structural self-reconstruction process. By conveying these insights, processes, general trends, and challenges, this review will further our understanding of surface reconstruction processes and facilitate the development of high-performance electrocatalysts beyond water oxidation.

Nanoparticles (NPs) are widely used in a variety of fields, including those related to consumer products, architecture, energy, and biomedicine. Once they enter the human body, NPs contact proteins in the blood and interact with cells in organs, which may induce cytotoxicity. Among the various factors of NP surface chemistry, surface charges, hydrophobicity levels and combinatorial decorations are found to play key roles inregulating typical cytotoxicity-related bioeffects, including protein binding, cellular uptake, oxidative stress, autophagy, inflammation, and apoptosis. In this review, we summarize the recent progress made in directing the levels and molecular pathways of these cytotoxicity-related effects by the purposeful design of NP surface charge, hydrophobicity, and combinatorial decorations.

Recent advancements in electrocatalysis have highlighted the exceptional application value of amorphous electrocatalysts. With their unique atomic configurations, these electrocatalysts exhibit superior catalytic performance compared to that of their crystalline counterparts. Transition metal (TM) amorphous ribbon-shaped electrocatalysts have recently emerged as a new frontier in the catalysis field. Dealloying is widely considered a fascinating method for enhancing the electrocatalyst performance. In this review, we comprehensively examine the principles of water electrolysis, discuss the prevalent methods for fabricating ribbon-configured electrocatalysts, and provide an overview of amorphous alloys. Furthermore, we discuss binary, ternary, and high-entropy amorphous TM-based electrocatalysts, which satisfy the requirements necessary for effective water electrolysis. We also propose strategies to enhance the activity of amorphous TM-based ribbons, including morphology control, defect engineering, composition optimization, and heterostructure creation in different electrolytes. Our focus extends to the latest developments in the design of heterogeneous micro/nanostructures, management of preparation techniques, and synthesis of different compositions. Finally, we address the ongoing challenges and provide a perspective on the future development of broadly applicable, self-supporting TM ribbon-shaped electrocatalysts.

Most electrocatalysts are known to experience structural change during the oxygen evolution reaction (OER) process. Considerable endeavors have been dedicated thus far to comprehending the catalytic process and uncovering the underlying mechanism. During the dynamic evolution of catalyst structure, component leaching of electrocatalysts is the most common phenomenon. This article offers a concise overview of recent findings and developments related to the leaching phenomena in the OER process in terms of fundamental understanding of leaching, advanced characterization techniques used to investigate leaching, leaching of inactive components, and leaching of active components. Leaching behaviors and the induced effects in various kinds of OER catalysts are discussed, progress in manipulating leaching amount/degree toward a tunable surface evolution is spotlighted, and finally, three representative types of structure transformations induced by leaching metastable species in OER condition are proposed. By understanding the process of component leaching in the OER, it will provide more guidance for the rational design of superior electrocatalysts. Most catalysts have been observed to undergo surface reconstruction in water oxidation. During the structure evolution of catalysts, component leaching is the most common phenomenon. This review provides an overview of component leaching of electrocatalysts in electrochemical water oxidation, and three representative types of structure transformations induced by leaching metastable species are summed up.