Over the past few decades, development of electrocatalysts for energy applications has extensively transitioned from trial-and-error methodologies to more rational and directed designs at the atomic levels via either nanogeometric optimization or modulating electronic properties of active sites. Regarding the modulation of electronic properties, nonprecious transition metal-based materials have been attracting large interest due to the capability of versatile tuning d-electron configurations expressed through the flexible orbital occupancy and various possible degrees of spin polarization. Herein, recent advances in tailoring electronic properties of the transition-metal atoms for intrinsically enhanced electrocatalytic performances are reviewed. We start with discussions on how orbital occupancy and spin polarization can govern the essential atomic level processes, including the transport of electron charge and spin in bulk, reactive species adsorption on the catalytic surface, and the electron transfer between catalytic centers and adsorbed species as well as reaction mechanisms. Subsequently, different techniques currently adopted in tuning electronic structures are discussed with particular emphasis on theoretical rationale and recent practical achievements. We also highlight the promises of the recently established computational design approaches in developing electrocatalysts for energy applications. Lastly, the discussion is concluded with perspectives on current challenges and future opportunities. We hope this review will present the beauty of the structure–activity relationships in catalysis sciences and contribute to advance the rational development of electrocatalysts for energy conversion applications.

renewable electricity into hydrogen fuel, while the latter plays an indispensable role in eco-friendly fuel cells and metalair batteries. [2] However, the fundamental electrode reactions that lie at the heart of these technologies, including the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and oxygen evolution reaction (OER), are inherently slow. Thus, high-performance electrocatalysts are inevitably required to accelerate the reaction kinetics, enhance the Faradaic efficiency, and minimize the Ohmic losses. Extensive research has revealed numerous electrocatalysts that drive these critical reactions. One such group of electrocatalysts-Platinum group metals (PGMs)-based materialsis extensively recognized for their optimal functionality, close-to-zero overpotentials, and excellent intrinsic activities. [3] Nevertheless, the high cost associated with using the resource-scarce PGMs significantly hinders the large-scale implementation of the technologies. [4] Therefore, it is crucial to improve the efficiency of PGM-based electrocatalysts via optimizing the intrinsic activity, maximizing atomic utilization, and enhancing operational stability. Furthermore, developing an electrocatalyst with multifunctionality is highly desirable to Developing highly efficient multifunctional electrocatalysts is crucial for future sustainable energy pursuits, but remains a great challenge. Herein, a facile synthetic strategy is used to confine atomically thin Pd-PdO nanodomains to amorphous Ru metallene oxide (RuO 2 ). The as-synthesized electrocatalyst (Pd 2 RuOx-0.5 h) exhibits excellent catalytic activity toward the pH-universal hydrogen evolution reaction (η 10 = 14 mV in 1 m KOH, η 10 = 12 mV in 0.5 m H 2 SO 4 , and η 10 = 22 mV in 1 m PBS), alkaline oxygen evolution reaction (η 10 = 225 mV), and overall water splitting (E 10 = 1.49 V) with high mass activity and operational stability. Further reduction endows the material (Pd 2 RuOx-2 h) with a promising alkaline oxygen reduction activity, evidenced by high halfway potential, four-electron selectivity, and excellent poison tolerance. The enhanced catalytic activity is attributed to the rational integration of favorable nanostructures, including 1) the atomically thin nanosheet morphology, 2) the coexisting amorphous and defective crystalline phases, and 3) the multi-component heterostructural features. These structural factors effectively regulate the material's electronic configuration and the adsorption of intermediates at the active sites for favorable reaction energetics.

Designing efficient bifunctional electrocatalysts with excellent activity and robust stability presents a central challenge for the large‐scale commercialization of water electrolysis. Herein, a facile approach is reported for the construct of atomically thin amorphous RuM (MCo, Fe, or Ni) bimetallenes as high‐performance electrocatalysts toward both electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The RuCo bimetallene manifests excellent bifunctional activity characterized by low required overpotentials, superior price activity, robust electrochemical durability as well as a low cell potential water splitting performance, outperforming Pt/C and RuO2 benchmark catalysts. Combined operando X‐ray absorption spectroscopy  investigation and theoretical simulations reveal the synergism taking place between binary constituents, in which Co serves a promotive role along the HER/OER reaction pathway, contributing via optimal binding to *OH for facile water dissociation as well as modulating the Ru electronic structure favorably, hence rendering high activity catalytic centers for both the alkaline HER and OER.

Highly efficient and durable electrocatalysts are of the utmost importance for the sustainable generation of clean hydrogen by water electrolysis. Here, we present a report of an atomically thin rhodium metallene incorporated with oxygenbridged single atomic tungsten (Rh−O−W) as a high-performance electrocatalyst for pH-universal hydrogen evolution reaction. The Rh−O−W metallene delivers ascendant electrocatalytic HER performance, characterized by exceptionally low overpotentials, ultrahigh mass activities, excellent turnover frequencies, and robust stability with negligible deactivation, in pH-universal electrolytes, outperforming that of benchmark Pt/ C, Rh/C and numerous other reported precious-metal HER catalysts. Interestingly, the promoting feature of −O−W single atomic sites is understood via operando X-ray absorption spectroscopy characterization and theoretical calculations. On account of electron transfer and equilibration processes take place between the binary components of Rh−O−W metallenes, fine-tuning of the density of states and electron localization at Rh active sites is attained, hence promoting HER via a near-optimal hydrogen adsorption.

In this paper we present a methodology for learning user profiles from content shared by people on Social Platforms. Such profiles are specifically tailored to reflect the user's degree of interactivity related to the topics they are writing about. The main novelty in our work is the introduction of Linked Data in the content extraction process and the definition of a specific scores to measure expertise and interactivity.