Stabilizing Silicon Photocathodes by Solution-Deposited Ni–Fe Layered Double Hydroxide for Efficient Hydrogen Evolution in Alkaline Media

An important pathway toward cost-effective photoelectrochemical (PEC) solar water-splitting devices is to stabilize and catalyze silicon (Si) photocathodes for hydrogen evolution reaction (HER), especially in alkaline solutions. To date, the most stable Si photocathode in alkaline media is protected by the atomic layer deposited (ALD) dense TiO₂ layer and catalyzed by noble metal-based catalysts on top. However, the ALD process is difficult to scale up, and the noble metals are expensive. Herein, we report the first demonstration of using a scalable hydrothermal method to deposit earth-abundant NiFe layered double hydroxide (LDH) to simultaneously protect and catalyze Si photocathodes in alkaline solutions. The NiFe LDH-protected/catalyzed p-type Si photocathode shows a current density of 7 mA/cm² at 0 V vs RHE, an onset potential of ∼0.3 V vs RHE that is comparable to that of the reported p–n⁺ Si photocathodes, and durability of 24 h at 10 mA/cm² in 1 M KOH electrolyte

Encapsulation of Single Nanoparticle in Fast-Evaporating Micro-droplets Prevents Particle Agglomeration in Nanocomposites

This work describes the use of fast-evaporating micro-droplets to finely disperse nanoparticles (NPs) in a polymer matrix for the fabrication of nanocomposites. Agglomeration of particles is a key obstacle for broad applications of nanocomposites. The classical approach to ensure the dispersibility of NPs is to modify the surface chemistry of NPs with ligands. The surface properties of NPs are inevitably altered, however. To overcome the trade-off between dispersibility and surface-functionality of NPs, we develop a new approach by dispersing NPs in a volatile solvent, followed by mixing with uncured polymer precursors to form micro-droplet emulsions. Most of these micro-droplets contain no more than one NP per drop, and they evaporate rapidly to prevent the agglomeration of NPs during the polymer curing process. As a proof of concept, we demonstrate the design and fabrication of TiO₂ NP@­PDMS nanocomposites for solar fuel generation reactions with high photocatalytic efficiency and recyclability arising from the fine dispersion of TiO₂. Our simple method eliminates the need for surface functionalization of NPs. Our approach is applicable to prepare nanocomposites comprising a wide range of polymers embedded with NPs of different composition, sizes, and shapes. It has the potential for creating nanocomposites with novel functions

Graphene/Acid Coassisted Synthesis of Ultrathin MoS₂ Nanosheets with Outstanding Rate Capability for a Lithium Battery Anode

Morphology-controlled MoS₂ nanosheets were successfully synthesized with the aid of graphene/acid coexistence by a one-pot hydrothermal method. The ultrathin MoS₂ nanosheets were self-assembled into a cockscomb-like structure with an exposed (100) facet on graphene sheets, which is in strong contrast to large aggregate MoS₂ plates grown freely on graphene sheets without acetic acid. The ultrathin MoS₂ nanosheets displayed excellent rate performance for Li storage (709 mAh·g^–1 capacity at 8320 mA·g^–1 discharging rate) and superior charge/discharge cyclability