Catalyst overcoating engineering towards high-performance electrocatalysis

Clean and sustainable energy needs the development of advanced heterogeneous catalysts as they are of vital importance for electrochemical transformation reactions in renewable energy conversion and storage devices. Advances in nanoscience and material chemistry have afforded great opportunities for the design and optimization of nanostructured electrocatalysts with high efficiency and practical durability. In this review article, we specifically emphasize the synthetic methodologies for the versatile surface overcoating engineering reported to date for optimal electrocatalysts. We discuss the recent progress in the development of surface overcoating-derived electrocatalysts potentially applied in polymer electrolyte fuel cells and water electrolyzers by correlating catalyst intrinsic structures with electrocatalytic properties. Finally, we present the opportunities and perspectives of surface overcoating engineering for the design of advanced (electro)catalysts and their deep exploitation in a broad scope of applications.

Hexagonal Boron Nitride Meeting Metal: A New Opportunity and Territory in Heterogeneous Catalysis

Two dimensional (2D) hexagonal boron nitride (h-BN) has been ignored for a long time in catalysis research because of its chemical inertness. Recently there has been a significant advance highlighting the role of metal/h-BN interfaces in catalytic applications. In this Perspective, we summarize state-of-the-art progress regarding h-BN-involved metal catalysts. Vacancy- and defect-rich h-BN sheets are able to anchor and modify supported metals, in which the interfacial metal-support interaction effect helps to enhance catalytic performance. Oxidative etching of h-BN sheets causes encapsulation of metal catalysts via boron oxide (BO_x) species, which work synergistically with neighboring metal sites in catalysis. Covering a metal surface with ultrathin h-BN shells creates a 2D nanoreactor featuring confinement effect, providing a novel way to modulate metal-catalyzed reactions. Given all those fascinating combinations of metal catalyst and h-BN, the emerging opportunity when h-BN meets metal in heterogeneous catalysis is clearly underlined. The outlook, especially the challenges in the field, are discussed as well.

Studies of exsolution and catalytic activity of metal nanocatalysts from parent perovskite

The synthesis of metal nanocatalysts exsolved from A-site deficient lanthanum strontium titanate (La_0.4Sr_0.4)(Ni_xTi_1−x)O_3−γ (LST, x = 0, LSTN, x = 0.06, 0.25, 0.5) perovskites and their catalytic properties were presented.

Oscillating syngas production on NiO/YSZ catalyst from methane oxidation

Synthesis gas was produced by methane oxidation on a NiO/YSZ cermet by interrupting the oxygen flow. Stopping the oxygen flow provoked the diffusion of lattice oxygen in the cermet, which in turn replenished the Ni–O bond that was consumed by methane. Resuming the oxygen flow brought about the activation of oxygen on the extrinsic vacancy site of YSZ. The activation, followed by the diffusion of oxygen and a Ni/NiO redox cycle, led to oscillatory syngas production. The infrared and mass spectroscopy results provide the reaction mechanism that governs the oxidation of methane on the NiO/YSZ cermet. This study presents a technique that can be applied to the catalysis of other metal/anion or cation conductor systems.

Synthesis gas was produced by methane oxidation on a NiO/YSZ cermet by interrupting the oxygen flow.

Facile Fabrication of BCN Nanosheet-Encapsulated Nano-Iron as Highly Stable Fischer-Tropsch Synthesis Catalyst

The few layered boron carbon nitride nanosheets (BCNNSs) have attracted widespread attention in the field of heterogeneous catalysis. Herein, we report an innovative one-pot route to prepare the catalyst of BCNNSs-encapsulated sub-10 nm highly dispersed nanoiron particles. Then the novel catalyst was used in Fischer-Tropsch synthesis for the first time and it exhibited high activity and superior stability. At a high temperature of 320 °C, CO conversion could reach 88.9%, corresponding catalytic activity per gram of iron (iron time yield, FTY) of 0.9 × 10^-4 mol_CO g_Fe^-1 s^-1, more than 200 times higher than that of pure iron. Notably, no obvious deactivation was observed after 1000 h running. The enhanced stability of the catalyst can be ascribed to the special encapsulated structure. Furthermore, the formation mechanism of highly dispersed iron nanoparticle also was elaborated. This approach opens the way to designing metal nanoparticles with both high stability and reactivity for nanocatalysts in hydrogenation application.

Ultrathin N-rich boron nitride nanosheets supported iron catalyst for Fischer–Tropsch synthesis

The Fe/BNNSs catalysts were firstly fabricated for the Fischer–Tropsch synthesis, which exhibited appreciable FTS activity, selectivity and good stability over 270 h.