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The low‐energy electrochemical production of hydrogen peroxide (H2O2) has garnered significant attention as a viable alternative to traditional industrial routes, with the goal of achieving carbon neutrality. For their H2O2 selectivity in the two‐electron oxygen reduction reaction (ORR), the coordination environment of tungsten (W)‐based materials is critical. In this study, atomically dispersed W single atoms were immobilized on N‐doped carbon substrates by a facile pyrolysis method to obtain a W single‐atom catalyst (W‐SAC). The coordination environment of an isolated W single atom with a tetra‐coordinated porphyrin‐like structure in W‐SAC was determined by X‐ray photoelectron spectroscopy and X‐ray absorption spectroscopy analysis. Notably, the as‐prepared W‐SAC showed superior two‐electron ORR activity in 0.1 M KOH solution, including high onset potential (0.89 V), high H2O2 selectivity (82.5%), and excellent stability. By using differential phase contrast‐scanning transmission electron microscopy and density functional theory calculations, it is revealed that the charge symmetry‐breaking of W atoms changes the adsorption behavior of the intermediates, leading to enhanced reactivity and selectivity for two‐electron ORR. This work broadens the avenue for understanding the charge transfer of W‐based electrocatalytic materials and the in‐depth reaction mechanism of SACs in two‐electron ORR. [ABSTRACT FROM AUTHOR]

Polar materials with spontaneous polarization (Ps) have emerged as highly promising photocatalysts for efficient photocatalytic H2 evolution owing to the Ps‐enhanced photogenerated carrier separation. However, traditional inorganic polar materials often suffer from limitations such as wide band gaps and poor carrier transport, which hinders their photocatalytic H2 evolution efficiency. Here, we rationally synthesized a series of isostructural two‐dimensional (2D) aromatic Dion–Jacobson (DJ) perovskites, namely (2‐(2‐Aminoethyl)pyridinium)PbI4 (2‐APDPI), (3‐(2‐Aminoethyl)pyridinium)PbI4 (3‐APDPI), and (4‐(2‐Aminoethyl)pyridinium)PbI4 (4‐APDPI), where 2‐APDPI and 4‐APDPI crystalize in polar space groups with piezoelectric constants (d33) of approximately 40 pm V−1 and 3‐APDPI adopts a centrosymmetric structure. Strikingly, owing to the Ps‐facilitated separation of photogenerated carriers, polar 2‐APDPI and 4‐APDPI exhibit a 3.9‐ and 2.8‐fold increase, respectively, in photocatalytic H2 evolution compared to the centrosymmetric 3‐APDPI. As a pioneering study, this work provides an efficient approach for exploring new polar photocatalysts and highlights their potential in promoting photocatalytic H2 evolution. [ABSTRACT FROM AUTHOR]

Exploring the dynamic structural evolution of electrocatalysts during reactions represents a fundamental objective in the realm of electrocatalytic mechanism research. In pursuit of this objective, we synthesized PhenPtCl2 nanosheets, revealing a N2-Pt-Cl2 coordination structure through various characterization techniques. Remarkably, the electrocatalytic performance of these PhenPtCl2 nanosheets for hydrogen evolution reaction (HER) surpasses that of the commercial Pt/C catalyst across the entire pH range. Furthermore, our discovery of the dynamic coordination changes occurring in the N2-Pt-Cl2 active sites during the electrocatalytic process, as clarified through in situ Raman and X-ray photoelectron spectroscopy, is particularly noteworthy. These changes transition from Phen-Pt-Cl2 to Phen-Pt-Cl and ultimately to Phen-Pt. The Phen-Pt intermediate plays a pivotal role in the electrocatalytic HER, dynamically coordinating with Cl- ions in the electrolyte. Additionally, the unsaturated, two-coordinated Pt within Phen-Pt provides additional space and electrons to enhance both H+ adsorption and H2 evolution. This research illuminates the intricate dynamic coordination evolution and structural adaptability of PhenPtCl2 nanosheets, firmly establishing them as a promising candidate for efficient and tunable electrocatalysts. Exploring the dynamic structural evolution of electrocatalysts during electrochemical reactions is imperative. Here, the authors constructed 2D PhenPtCl2 nanosheets with Phen-Pt-Cl2 coordination structure which exhibit dynamic coordination evolution during hydrogen evolution reaction and good performance across the full pH range [ABSTRACT FROM AUTHOR]

Defect engineering is an effective strategy to improve the activity of two-dimensional molybdenum disulfide base planes toward electrocatalytic hydrogen evolution reaction. Here, we report a Frenkel-defected monolayer MoS2 catalyst, in which a fraction of Mo atoms in MoS2 spontaneously leave their places in the lattice, creating vacancies and becoming interstitials by lodging in nearby locations. Unique charge distributions are introduced in the MoS2 surface planes, and those interstitial Mo atoms are more conducive to H adsorption, thus greatly promoting the HER activity of monolayer MoS2 base planes. At the current density of 10 mA cm−2, the optimal Frenkel-defected monolayer MoS2 exhibits a lower overpotential (164 mV) than either pristine monolayer MoS2 surface plane (358 mV) or Pt-single-atom doped MoS2 (211 mV). This work provides insights into the structure-property relationship of point-defected MoS2 and highlights the advantages of Frenkel defects in tuning the catalytic performance of MoS2 materials. While material defect sites are active for chemical reactions, it is important to understand how different defect types impact reactivity. Here, authors prepare Frenkel-defected MoS2 monolayers and demonstrate improved performances for H2 evolution electrocatalysis than pristine or doped MoS2. [ABSTRACT FROM AUTHOR]

The electrochemical co‐synthesis of H₂O₂ and O₃ holds substantial potential for environmental sustainability and energy conservation. However, synthesizing electrocatalysts with appropriate adsorption energies for intermediates in the electrochemical pairwise electrosynthesis of H₂O₂ and O₃ remains a major challenge. In this study, boron and nitrogen‐doped 2D diamonds (BND) and atomically dispersed Pt₁/BND electrocatalysts are systematically designed and synthesized to facilitate the two‐electron oxygen reduction reaction (2e⁻ ORR) and electrochemical ozone production (EOP), respectively. The BND and Pt₁/BND electrocatalysts exhibit remarkable electrochemical activity, with BND achieving 90.7% selectivity for H₂O₂ and Pt₁/BND attaining a Faradaic efficiency (FE) of 12.54% for EOP. The Pt monatomic species, with a loading of 0.13%, are predominantly distributed along the edges of the Pt₁/BND. Theoretical calculations reveal that their superior properties primarily stem from the phase transition to graphene fractions at the edges, which facilitate moderate adsorption of oxygen intermediates and modulate the electronic structure through synergistic interactions between the dopant elements. Additionally, the 2D diamonds exhibit favorable mass transfer properties. The integration of H₂O₂ and O₃ for the synergistic degradation of organic contaminants and sterilization further showcase the practical utility of BND and Pt₁/BND electrocatalysts. [ABSTRACT FROM AUTHOR]

Polar materials with spontaneous polarization (P s ) have emerged as highly promising photocatalysts for efficient photocatalytic H 2 evolution owing to the P s -enhanced photogenerated carrier separation. However, traditional inorganic polar materials often suffer from limitations such as wide band gaps and poor carrier transport, which hinders their photocatalytic H 2 evolution efficiency. Here, we rationally synthesized a series of isostructural two-dimensional (2D) aromatic Dion-Jacobson (DJ) perovskites, namely (2-(2-Aminoethyl)pyridinium)PbI 4 (2-APDPI), (3-(2-Aminoethyl)pyridinium)PbI 4 (3-APDPI), and (4-(2-Aminoethyl)pyridinium)PbI 4 (4-APDPI), where 2-APDPI and 4-APDPI crystalize in polar space groups with piezoelectric constants (d 33 ) of approximately 40 pm V -1 and 3-APDPI adopts a centrosymmetric structure. Strikingly, owing to the P s -facilitated separation of photogenerated carriers, polar 2-APDPI and 4-APDPI exhibit a 3.9- and 2.8-fold increase, respectively, in photocatalytic H 2 evolution compared to the centrosymmetric 3-APDPI. As a pioneering study, this work provides an efficient approach for exploring new polar photocatalysts and highlights their potential in promoting photocatalytic H 2 evolution., (© 2024 Wiley‐VCH GmbH.)