Two-dimensional transition metal hydroxides with abundant reserves and low prices have played an indispensable role in energy catalytic applications. Recent reports indicated that the incorporation of Fe species into Co-based catalysts can synergistically enhance oxygen evolution reaction (OER) activity. Constructing a heterointerface on the surface of Co-based catalysts can provide a platform to investigate the role of heterointerface in reaction kinetics. Herein, we constructed a Fe-O-Co heterointerface without electronic effect by depositing FeO_x clusters on the oxygen vacancies of CoOOH surface. FeO_x/CoOOH exhibited excellent OER intrinsic activity, which can deliver the turnover frequency (TOF) of 4.56 s⁻¹ at the overpotentials of 300 mV and the Tafel slope of 33 mV·dec⁻¹. In-situ electrochemical impedance spectroscopy (EIS) and density functional theory (DFT) calculations demonstrated that the synergistic effect between Fe sites and Co sites confined at the Fe-O-Co heterointerface accelerated the charge transfer during OER and optimized the adsorption of oxygen intermediates, consequently enhancing OER.

Bi is one of the most fascinating catalysts for the formation of HCOO⁻ towards CO₂ electroreduction. Herein, we developed electrodeposited angular-shaped Bi microparticles (Bi MP) with exposed surfaces of {003} and {101} planes as efficient catalyst for the electroreduction of CO₂ into HCOO⁻. During CO₂ electroreduction, Bi MP achieved a Faraday efficiency (FE) for HCOO⁻ of higher than 95% over a wide range of applied potential from −0.6 to −1.1 V versus reversible hydrogen electrode (vs. RHE), whereas the FE for HCOO⁻ of Bi nanoflakes (Bi NF) with exposed surfaces of {104} and {110} planes was around 70%. At −1.1 V vs. RHE, the partial current density for HCOO⁻ of Bi MP was −271.7 mA·cm⁻², 1.56 times as high as that of Bi NF. According to kinetic analysis and mechanistic study, highly-oriented surface of Bi MP not only facilitated Faradaic process and accelerated reaction kinetics via enhancing the CO₂ activation, but also restrained competing hydrogen evolution reaction, thus boosting catalytic performance of the electroreduction of CO₂ into HCOO⁻.

Nanomaterials with unique edge sites have received increasing attention due to their superior performance in various applications. Herein, we employed an effective ethylenediaminetetraacetic acid (EDTA)-assisted method to synthesize a series of exotic Bi₂Se₃ nanostructures with distinct edge sites. It was found that the products changed from smooth nanoplates to half-plate-containing and crown-like nanoplates upon increasing the molar ratio of EDTA to Bi³⁺. Mechanistic studies indicated that, when a dislocation source and relatively high supersaturation exist, the step edges in the initially formed seeds can serve as supporting sites for the growth of epilayers, leading to the formation of half-plate-containing nanoplates. In contrast, when the dislocation source and a suitably low supersaturation are simultaneously present in the system, the dislocation-driven growth mode dominates the process, in which the step edges form at the later stage of the growth responsible for the formation of crown-like nanoplates.

Shape control has proven to be a powerful and versatile means of tailoring the properties of Bi₂Se₃ nanostructures for a wide variety of applications. Here, three different Bi₂Se₃ nanostructures, i.e., spiral-type nanoplates, smooth nanoplates, and dendritic nanostructures, were prepared by manipulating the supersaturation level in the synthetic system. This mechanism study indicated that, at low supersaturation, defects in the crystal growth could cause a step edge upon which Bi₂Se₃ particles were added continuously, leading to the formation of spiral-type nanoplates. At intermediate supersaturation, the aggregation of amorphous Bi₂Se₃ particles and subsequent recrystallization resulted in the formation of smooth nanoplates. Furthermore, at high supersaturation, polycrystalline Bi₂Se₃ cores formed initially, on which anisotropic growth of Bi₂Se₃ occurred. This work not only advances our understanding of the growth mechanism but also offers a new approach to control the morphology of Bi₂Se₃ nanostructures.

The synthesis of highly uniform alloy nanocrystals with a concave feature is desirable for applications in catalysis but is an arduous task. This article proposes an initiative protocol for the fabrication of novel Cu-Pd alloy nanocrystals, wherein the volume of decylamine (DA) in the reaction system was found to greatly influence the formation of different morphologies, including the tetrahedron (TH), concave tetrahedron (CTH), rhombohedral-tetrapod (RTP), and tetrapod (TP). The alloy structure of the products arises from the coordination interaction between the DA and metal ions, which affects the reduction potential of Cu and Pd species, and thus yields co-reduction. Other reaction parameters, such as the type of ligand, amount of reductant, and temperature, were also altered to study the growth mechanism, yielding consistent conclusions in the diffusion-controlled regime. As a catalyst, 48-nm Cu-Pd concave tetrahedral nanocrystals were highly active for the hydrogenation of 3-nitrostyrene and exhibited > 99.9% chemoselectivity to C=C instead of -NO₂.

Modulation of the morphology of nanostructures is often a rewarding but challenging task. We have employed the seeded growth method and induced kinetic control to synthesize Bi₂Se₃ nanoplates with modifiable morphology. By manipulating the rate at which precursor solutions were injected into seeds solution with syringe pumps, two distinctive growth modes could be realized. With a fast injection, the thickness of Bi₂Se₃ nanoplates slightly increased from ~7.5 nm (seeds) to ~9.5 nm while the edge length grew up from ~160 nm (seeds) to ~12 μm, after 6 successive rounds of seeded growth. With a slow injection, the thickness and edge length increased simultaneously to ~35 nm and ~6 μm after 6 rounds of growth, respectively. These two modes could be viewed as a competition between atomic deposition and surface migration. The products showed interesting, thickness-dependent Raman properties. In addition, NIR transparent, highly conductive and flexible Bi₂Se₃ thin films with different thicknesses were constructed by the assembly of the as-synthesized Bi₂Se₃ nanoplates. This approach based on seeded growth and kinetic control can significantly promote the development of versatile nanostructures with diverse morphology.