Solar-driven hydrogen peroxide (H2O2) production presents unique merits of sustainability and environmental friendliness. Herein, efficient solar-driven H2O2 production through dioxygen reduction is achieved by employing polymeric carbon nitride framework with sodium cyanaminate moiety, affording a H2O2 production rate of 18.7 μmol h −1 mg−1 and an apparent quantum yield of 27.6% at 380 nm. The overall photocatalytic transformation process is systematically analyzed, and some previously unknown structural features and interactions are substantiated via experimental and theoretical methods. The structural features of cyanamino group and pyridinic nitrogen-coordinated soidum in the framework promote photon absorption, alter the energy landscape of the framework and improve charge separation efficiency, enhance surface adsorption of dioxygen, and create selective 2e− oxygen reduction reaction surface-active sites. Particularly, an electronic coupling interaction between O2 and surface, which boosts the population and prolongs the lifetime of the active shallow-trapped electrons, is experimentally substantiated.
Layered 2D materials are a vital class of electrocatalys for the hydrogen evolution reaction (HER), due to their large area, excellent activity, and facile fabrication. Theoretical caculations domenstrate, however, that only the edges of the 2D nanosheets act as active sites, while the much larger basal plane exhibits passive activity. Here, from a distinguishing perspective, RhSe2 is reported as a “3D” electrocatalyst for HER with top‐class activity, synthesized by a facile solid‐state method. Superior to 2D materials, multiple crystal facets of RhSe2 exhibit near‐zero free energy change of hydrogen adsorption (ΔGH), which guarantees high performance in most common morphologies. Density functional theory calculations reveal that the low‐coordinated Rh atoms act as the active sites in acid, which enables the modified Kubas‐mediated pathway, while the Se atoms act as the active sites in an alkaline medium. The overpotentials of HER activity of RhSe2 are measured to be 49.9 and 81.6 mV at 10 mA cm–2 in acid and alkaline solutions, respectively. This work paves the way to new transition metal chalcogenide catalysts.
PtSe 2 is atypical noble metal dichalcogenide (NMD) that holds promising possibility for next-generation electronics and photonics.H owever,w hen applied in hydrogen evolution reaction (HER), it exhibits sluggish kinetics due to the insufficient capability of absorbing active species.H ere,w e construct PtSe 2 /Pt heterointerface to boost the reaction dynamics of PtSe 2 ,enabled by an in situ electrochemical method. It is found that Se vacancies are induced around the heterointerface,reducing the coordination environment. Correspondingly,the exposed Pt atoms at the very vicinity of Se vacancies are activated, with enhanced overlap with H1 so rbital. The adsorption of H C intermediate is thus strengthened, achieving near thermoneutral free energy change.C onsequently,t he asprepared PtSe 2 /Pt exhibits extraordinary HER activity even superior to Pt/C,with an overpotential of 42 mV at 10 mA cm À2 and aT afel slope of 53 mV dec À1 .This work raises attention on NMDs toward HER and provides insights for the rational construction of novel heterointerfaces.
Alloying techniques show genuine potential to develop more effective catalysts than Pt for oxygen reduction reaction (ORR), which is the key challenge in many important electrochemical energy conversion and storage devices, such as fuel cells and metal‐air batteries. Tremendous efforts have been made to improve ORR activity by designing bimetallic nanocatalysts, which have been limited to only alloys of platinum and transition metals (TMs). The Pt‐TM alloys suffer from critical durability in acid‐media fuel cells. Here a new class of mesostructured Pt–Al catalysts is reported, consisting of atomic‐layer‐thick Pt skin and Pt3Al or Pt5Al intermetallic compound skeletons for the enhanced ORR performance. As a result of strong Pt–Al bonds that inhibit the evolution of Pt skin and produce ligand and compressive strain effects, the Pt3Al and Pt5Al mesoporous catalysts are exceptionally durable and ≈6.3‐ and ≈5.0‐fold more active than the state‐of‐the‐art Pt/C catalyst at 0.90 V, respectively. The high performance makes them promising candidates as cathode nanocatalysts in next‐generation fuel cells.
Applications of rechargeable non-lithium-ion batteries (Na, K, Ca, Mg, and Al NLIBs) are significantly hampered by the deficiency of suitable electrode materials. Searching for anode materials with desirable electrochemical performance is urgent for the large-scale energy storage demands of next generation renewable energy technologies. In this study, three types of recently synthesized borophenes are predicted to serve as high-performing anodes for NLIBs based on density functional theory. All the borophenes considered here are metallic with favorable in-plane stiffness. Dirac fermions were identified in two types of borophenes, guaranteeing their high electron mobility. Moreover, borophene configuration-dependent metal-ion migration, theoretical capacities, and open-circuit voltages were demonstrated with respect to the different adsorption behaviors and atom mass densities of anode materials. Our results provide insights into the configuration-dependent electrode performance of borophene and the corresponding metal-ion storage mechanism.
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