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Pd catalysts display excellent potential applications in H 2 O 2 direct synthesis from H 2 and O 2 . Facet dependence on catalytic selectivity for H 2 O 2 direct synthesis on Pd surfaces is investigated by the combination of DFT calculations and microkinetic study. It is found that the coadsorbed O plays a key role in catalytic activity and selectivity for H 2 O 2 direct synthesis on Pd(111) and Pd(100) surfaces. The coadsorbed O on Pd surfaces could not only increase the catalytic activity but also promote the catalytic selectivity on Pd surfaces. With the help of coadsorbed O, Pd(111) surface shows a very high selectivity (>99%) for H 2 O 2 products, but Pd(100) surface displays a high selectivity (>99%) for H 2 O formation. The role of proton transfer is also investigated in H 2 O 2 direct synthesis, and it is found that proton transfer reactions are harmful to H 2 O 2 formation. This work sheds light on the reaction mechanism of H 2 O 2 direct synthesis reaction on different Pd surfaces, and it may create a new path to understand the facet-dependent on catalytic selectivity.

Black phosphorus (BP) has become one of the most promising materials for photoelectronic devices due to its excellent properties. However, the intrinsic instability of BP has severely hindered its practical applications. In this contribution, a hydrophobic polyionic liquid poly(1-hexyl-3-vinylimidazolium) hexafluorophosphate salt (PIL-TFSI) is applied to encapsulate BP quantum dots to form BP-PIL for photo-electrochemical-type photodetector (PD) application. From both the results of experiment and density functional theory, the significantly enhanced stability of BP as well as the fluorination of BP is found. The asprepared PDs exhibit obviously improved photoresponse behavior (542 nA cm −2 ) and negligible attenuation after 90 days. In addition, the self-healing capability can be found in the prepared PDs and the typical ON/OFF signals can still be detected after 50 cycles due to the self-healing nature of PIL-TFSI. It is believed that the introduction of PIL-TFSI provides a new route for enhancing the stability of BP-based photoelectronic devices in practical applications.

Heterojunctions, composed of different materials, are widely explored in optoelectronic devices thanks to their unique advantages, such as high carrier mobility and excellent photoelectronic characteristics. In this work, Bi2Se3/Te@Se heterojunctions (Bi2Se3/Te@Se) are synthesized through the epitaxial growth of Bi2Se3 nanosheets (Bi2Se3 NTs) on tellurium@selenium nanotubes (Te@Se NTs) by using a low‐cost and facile solvothermal process. Bi2Se3/Te@Se are further applied in high‐performance photoelectrochemical (PEC)‐type photodetection due to the advantages of broadband optical response and fast carrier relaxation time. The PEC results demonstrate that the as‐prepared photodetectors have pronounced photoresponse behavior from the ultraviolet to visible band with self‐driven ability and excellent long‐term stability. It is anticipated that this work provides a new strategy for epitaxial growth of topological insulators on semiconductors for designing new heterojunctions toward high‐performance optoelectronic devices.

We investigate the cohesive energy, heat of formation, elastic constant and electronic band structure of transition metal diborides TMB2 (TM =  Hf, Ta, W, Re, Os and Ir, Pt) in the Pmmn space group using the ab initio pseudopotential total energy method. Our calculations indicate that there is a relationship between elastic constant and valence electron concentration (VEC): the bulk modulus and shear modulus achieve their maximum when the VEC is in the range of 6.8–7.2. In addition, trends in the elastic constant are well explained in terms of electronic band structure analysis, e.g., occupation of valence electrons in states near the Fermi level, which determines the cohesive energy and elastic properties. The maximum in bulk modulus and shear modulus is attributed to the nearly complete filling of TM d–B p bonding states without filling the antibonding states. On the basis of the observed relationship, we predict that alloying W and Re in the orthorhombic structure OsB2 might be harder than alloying the Ir element. Indeed, the further calculations confirmed this expectation.