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Introducing cerium (Ce) species into electrocatalysts has been recently developed as an effective approach to improve their oxygen evolution reaction (OER) performance. Importantly, the spatial distribution of Ce species in the hosts can determine the availability of Ce species either as additives or as co-catalysts, which would dictate their different contributions to the enhanced electrocatalytic performance. Herein, the comprehensive investigations on two different catalyst configurations, namely CeO₂-embedded NiO (Ce-NiO-E) and CeO₂-surface-loaded NiO (Ce-NiO-L), are performed to understand the effect of their specific spatial arrangements on OER characteristics. The Ce-NiO-E catalysts exhibit a smaller overpotential of 382 mV for 10 mA cm⁻² and a lower Tafel slope of 118.7 mV dec⁻¹, demonstrating the benefits of the embedded configuration for OER, as compared with those of Ce-NiO-L (426 mV and 131.6 mV dec⁻¹) and pure NiO (467 mV and 140.7 mV dec⁻¹), respectively. The improved OER property of Ce-NiO-E originates from embedding small-sized CeO₂ clusters into the host for the larger specific surface area, richer surface defects, higher oxygen adsorption capacity, and better optimized electronic structures of the surface active sites, as compared with Ce-NiO-L. Above findings provide a valuable guideline for and insight in designing catalysts with different spatial configurations for enhanced catalytic properties.

Spatial distribution of CeO₂ species as additives in the NiO host can dictate different contributions to the enhanced electrocatalytic oxygen evolution performance. The comparative study on two different catalyst configurations showed the benefits of embedding small-sized CeO₂ clusters into NiO to modify the surface properties and structures and improve the activity as compared with CeO₂ surface-loaded NiO.

Nickel sulfide (Ni₃S₂) is a promising hydrogen evolution reaction (HER) catalyst by virtue of its metallic electrical conductivity and excellent stability in alkaline medium. However, the reported catalytic activities for Ni₃S₂ are still relatively low. Herein, an effective strategy to boost the H adsorption capability and HER performance of Ni₃S₂ through nitrogen (N) doping is demonstrated. N-doped Ni₃S₂ nanosheets achieve a fairly low overpotential of 155 mV at 10 mA cm⁻² and an excellent exchange current density of 0.42 mA cm⁻² in 1.0 m KOH electrolyte. The mass activity of 16.9 mA mg⁻¹ and turnover frequency of 2.4 s⁻¹ obtained at 155 mV are significantly higher than the values reported for other Ni₃S₂-based HER catalysts, and comparable to the performance of best HER catalysts in alkaline medium. These experimental data together with theoretical analysis suggest that the outstanding catalytic activity of N-doped Ni₃S₂ is due to the enriched active sites with favorable H adsorption free energy. The activity in the Ni₃S₂ is highly correlated with the coordination number of the surface S atoms and the charge depletion of neighbor Ni atoms. These new findings provide important guidance for future experimental design and synthesis of optimal HER catalysts.

Nitrogen-doped Ni₃S₂ nanosheets achieve excellent hydrogen evolution reaction (HER) performance in alkaline media. Both experimental and theoretical investigations suggest that the improved activity of nitrogen-doped Ni₃S₂ originates from enriched new active sites with favorable H adsorption. These new findings make inexpensive Ni₃S₂ more attractive and provide important guidance for future experimental design and synthesis of Ni₃S₂-based HER catalysts.

Metal–organic frameworks (MOFs) are an emerging class of porous materials with potential applications in gas storage, separations, catalysis, and chemical sensing. Despite numerous advantages, applications of many MOFs are ultimately limited by their stability under harsh conditions. Herein, the recent advances in the field of stable MOFs, covering the fundamental mechanisms of MOF stability, design, and synthesis of stable MOF architectures, and their latest applications are reviewed. First, key factors that affect MOF stability under certain chemical environments are introduced to guide the design of robust structures. This is followed by a short review of synthetic strategies of stable MOFs including modulated synthesis and postsynthetic modifications. Based on the fundamentals of MOF stability, stable MOFs are classified into two categories: high-valency metal–carboxylate frameworks and low-valency metal–azolate frameworks. Along this line, some representative stable MOFs are introduced, their structures are described, and their properties are briefly discussed. The expanded applications of stable MOFs in Lewis/Brønsted acid catalysis, redox catalysis, photocatalysis, electrocatalysis, gas storage, and sensing are highlighted. Overall, this review is expected to guide the design of stable MOFs by providing insights into existing structures, which could lead to the discovery and development of more advanced functional materials.

Stable metal–organic frameworks (MOFs) with high resistance to harsh chemical environments are reviewed with regard to recent progress in their research and development. Fundamental mechanisms of MOF stability, design and synthesis of stable MOF architectures, and their latest applications are summarized, providing a fundamental outline for the discovery of new stable MOFs.

Photocatalytic hydrogen production is crucial for solar-to-chemical conversion process, wherein high-efficiency photocatalysts lie in the heart of this area. A photocatalyst of hierarchically mesoporous titanium phosphonate based metal–organic frameworks, featuring well-structured spheres, a periodic mesostructure, and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well-structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemistry.

A multi-structured photocatalyst: A metal–organic framework (MOF) nanostructure synthesized by a surfactant-directed strategy features a stable framework of titanium phosphates, a well-defined sphere, and hierarchical nanopores. These features ensure competitive photoactivity in evolving hydrogen under both visible light and full-spectrum simulator irradiation, along with high durability.