Enhancing Photocatalytic Overall Water Splitting Activity of SrTiO₃ Nanoparticles by a Synergetic Pt/CrOx Dual Cocatalyst System

Sunlight-driven photocatalytic overall water splitting (OWS) is a promising approach for solar-to-chemical energy conversion. However, its realization with a single photocatalyst by one-step excitation has been extremely limited due to the rapid recombination of photogenerated charges, slow surface redox kinetics, and undesired reverse reactions. Herein, we sought to enhance the OWS performance of SrTiO3 (STO) by exploring the synergistic effects of different kinds of metal/oxide dual cocatalysts. The results show that the Pt/CrOx-STO system had a superior activity, which achieved stoichiometric water splitting with H2/O2 evolution of 1814.17/1020.47 μmol g–1 h–1 under simulated sunlight, without using any sacrificial reagents. The enhanced efficiency can be attributed to the improved interfacial transport of photogenerated charges and the boosted surface kinetics. Importantly, the CrOx layer served as a selective membrane that prevented the O2 diffusion and facilitated H+ transport, while partially covering the highly active site of Pt nanoparticles, thus significantly inhibiting the reverse recombination reaction of H2 and O2. In particular, this dual catalyst system emphasized a low dependence on the properties of the substrate material and is therefore widely applicable and economical. This work demonstrated the potential of the Pt/CrOx dual cocatalyst modification strategy for optimizing photocatalytic OWS, providing a pathway toward selective and sustainable conversion of H2O to H2 and O2

Enhanced Catalytic Activities of NiPt Truncated Octahedral Nanoparticles toward Ethylene Glycol Oxidation and Oxygen Reduction in Alkaline Electrolyte

The high cost and poor durability of Pt nanoparticles (NPs) are great limits for the proton exchange membrane fuel cells (PEMFCs) from being scaled-up for commercial applications. Pt-based bimetallic NPs together with a uniform distribution can effectively reduce the usage of expensive Pt while increasing poison resistance of intermediates. In this work, a simple one-pot method was used to successfully synthesize ultrafine (about 7.5 nm) uniform NiPt truncated octahedral nanoparticles (TONPs) in dimethylformamid (DMF) without any seeds or templates. The as-prepared NiPt TONPs with Pt-rich surfaces exhibit greatly improved catalytic activities together with good tolerance and better stability for ethylene glycol oxidation reaction (EGOR) and oxygen reduction reaction (ORR) in comparison with NiPt NPs and commercial Pt/C catalysts in alkaline electrolyte. For example, the value of mass and specific activities for EGOR are 23.2 and 17.6 times higher comparing with those of commercial Pt/C, respectively. Our results demonstrate that the dramatic enhancement is mainly attributed to Pt-rich surface, larger specific surface area, together with coupling between Ni and Pt atoms. This developed method provides a promising pathway for simple preparation of highly efficient electrocatalysts for PEMFCs in the near future

Hierarchical Self-Assembly of Cu₇Te₅ Nanorods into Superstructures with Enhanced SERS Performance

This paper reports a strategy to get self-assembly of Cu₇Te₅ nanorods into hierarchical superstructures: the side-by-side self-assembly of nanorods into microscale one-dimensional (1D) nanowires (primary structure), the side-by-side alignments of the 1D nanowires into two-dimensional (2D) nanowire bundles (secondary structure), and the further rolling up of the 2D bundles into three-dimensional (3D) microtubes (tertiary structure). It was found that the oleylamine (OLA)/n-dodecanethiol (DDT) mixture as a binary capping agent was key to produce Cu₇Te₅ nanorods in the quantum size regime with high monodispersity, and this was a prerequisite for their hierarchical self-assembly based on elaborate control of the solvent evaporation process. The obtained Cu₇Te₅ microtube superstructures were used as SERS substrate and showed much stronger SERS enhancement than the as-prepared Cu₇Te₅ nanorods before assembly. This was probably ascribed to the remarkably enhanced local electromagnetic field arising from the plasmon coupling of Cu₇Te₅ nanorods in the well-assembled superstructures

Mixed-Dimensional van der Waals Heterostructure for High-Performance and Air-Stable Perovskite Nanowire Photodetectors

An organic–inorganic hybrid perovskite nanowire (NW), CH3NH3PbI3, shows great potential for high-performance photodetectors due to its excellent photoresponse. However, the inefficient carrier collection between the one-dimensional (1D) NWs and metallic electrodes, as well as degradation of the perovskite, limits the viability of the CH3NH3PbI3 NWs for commercial production. Here, we demonstrate a photodetector with a mixed-dimensional van der Waals heterostructure of hexagonal boron nitride (hBN)/graphene (Gr)/1D CH3NH3PbI3, which exhibits excellent responsivity and specific detectivity of up to 558 A/W and 2.3 × 1012 Jones, owing to the improved carrier extraction at the electrical contact between Gr and the NW. As for the atomic encapsulation of hBN, the device is extremely robust and maintains its outstanding performance for more than 2 months when exposed to air. Moreover, benefitting from the 1D geometry of the CH3NH3PbI3 NW, our device is highly sensitive to polarized light. The mixed-dimensional van der Waals heterostructure, hBN/Gr/1D CH3NH3PbI3, would provide a novel idea and protocol for fabricating high-performance and air-stable photoelectronic devices based on organic–inorganic hybrid perovskite NWs

Controllable Spin–Orbit Torque Induced by Interfacial Ion Absorption in Ta/CoFeB/MgO Multilayers with Canted Magnetizations

Electrically generated spin–orbit torque (SOT) has emerged as a powerful pathway to control magnetization for spintronic applications including memory, logic, and neurocomputing. However, the requirement of external magnetic fields, together with the ultrahigh current density, is the main obstacle for practical SOT devices. In this paper, we report that the field-free SOT-driven magnetization switching can be successfully realized by interfacial ion absorption in perpendicular Ta/CoFeB/MgO multilayers. Besides, the tunable SOT efficiency exhibits a strong dependence on interfacial Ti insertion thicknesses. Polarized neutron reflection measurements demonstrate the existence of canted magnetization with Ti inserted, which leads to deterministic magnetization switching. In addition, interfacial characterization and first-principles calculations reveal that B absorption by the Ti layer is the main cause behind the enhanced interfacial transparency, which determines the tunable SOT efficiency. Our findings highlight an attractive scheme to a purely electric control spin configuration, enabling innovative designs for SOT-based spintronics via interfacial engineering