Tuning the Potential Energy Landscape to Suppress Ostwald Ripening in Surface-Supported Catalyst Systems

Ultrafine oxygenophilic nanoalloys induced by multifunctional interstitial boron for methanol oxidation reaction

Interface construction is one of the most feasible approaches to optimize the physical and chemical properties of noble metal-based catalysts and consequently improve their catalytic performance. Herein, the design of effective reaction interfaces by bimetallic, trimetallic or polymetallic alloying has been extensively explored. In this research, metalloid boron (B) was alloyed within palladium-iridium (Pd-Ir) nanoalloy supported on nitrogen-doped graphene (NG) to promote the methanol oxidation reaction (MOR) in alkaline media. Being benefited from this, the optimum Pd7IrBx/NG catalyst exhibited enhanced EOR activity mass activity (1141.7 mA mg-1) and long-term stability (58.2 % current density retention rate after 500 cycles of cyclic voltammetry). The mechanism was further studied by electrochemical experiments and characterization, which highlighted that the multifunctional effect of electronic effect and strain effect and kinetic optimization induced by boron doping played a very positive role on MOR.

Genesis of Nanogalvanic Corrosion Revealed in Pearlitic Steel

Nanoscale, localized corrosion underpins billions of dollars in damage and material costs each year; however, the processes responsible have remained elusive due to the complexity of studying degradative material behavior at nanoscale liquid-solid interfaces. Recent improvements to liquid cell scanning/transmission electron microscopy and associated techniques enable this first look at the nanogalvanic corrosion processes underlying this widespread damage. Nanogalvanic corrosion is observed to initiate at the near-surface ferrite/cementite phase interfaces that typify carbon steel. In minutes, the corrosion front delves deeper into the material, claiming a thin layer of ferrite around all exposed phase boundaries before progressing laterally, converting the ferrite to corrosion product normal to each buried cementite grain. Over the following few minutes, the corrosion product that lines each cementite grain undergoes a volumetric expansion, creating a lateral wedging force that mechanically ejects the cementite grains from their grooves and leaves behind percolation channels into the steel substructure.

Nanoscale engineering of catalytic materials for sustainable technologies

Nanostructured materials of diverse architecture are ubiquitous in industrial catalysis. They offer exciting prospects to tackle various sustainability challenges faced by society. Since the introduction of the concept a century ago, researchers aspire to control the chemical identity, local environment and electronic properties of active sites on catalytic surfaces to optimize their reactivity in given applications. Nowadays, numerous strategies exist to tailor these characteristics with varying levels of atomic precision. Making headway relies upon the existence of analytical approaches able to resolve relevant structural features and remains challenging due to the inherent complexity even of the simplest heterogeneous catalysts, and to dynamic effects often occurring under reaction conditions. Computational methods play a complementary and ever-increasing role in pushing forward the design. Here, we examine how nanoscale engineering can enhance the selectivity and stability of catalysts. We highlight breakthroughs towards their commercialization and identify directions to guide future research and innovation.

Zeolite Nanosheets Stabilize Catalyst Particles to Promote the Growth of Thermodynamically Unfavorable, Small-Diameter Carbon Nanotubes

A challenge in the synthesis of single-wall carbon nanotubes (SWCNTs) is the lack of control over the formation and evolution of catalyst nanoparticles and the lack of control over their size or chirality. Here, zeolite MFI nanosheets (MFI-Ns) are used to keep cobalt (Co) nanoparticles stable during prolonged annealing conditions. Environmental transmission electron microscopy (ETEM) shows that the MFI-Ns can influence the size and shape of nanoparticles via particle/support registry, which leads to the preferential docking of nanoparticles to four or fewer pores and to the regulation of the SWCNT synthesis products. The resulting SWCNT population exhibits a narrow diameter distribution and SWCNTs of nearly all chiral angles, including sub-nm zigzag (ZZ) and near-ZZ tubes. Theoretical simulations reveal that the growth of these unfavorable tubes from unsupported catalysts leads to the rapid encapsulation of catalyst nanoparticles bearing them; their presence in the growth products suggests that the MFI-Ns prevent nanoparticle encapsulation and prologue ZZ and near-ZZ SWCNT growth. These results thus present a path forward for controlling nanoparticle formation and evolution, for achieving size- and shape-selectivity at high temperature, and for controlling SWCNT synthesis.