Porous Nanoarchitectures of Nonprecious Metal Borides: From Controlled Synthesis to Heterogeneous Catalyst Applications

Abstract

Porous nonprecious metal-based nanomaterials have gained considerable attention in heterogeneous catalysis owing to their low price, high specific surface area, efficient mass/electron transfer, tunable pore structure, and unique physicochemical properties. Controlling the phase and compositions of these porous nonprecious metal-based materials is critical to their applications. Porous nonprecious transition-metal borides (TMBs), typical metal−metalloid alloys, have recently received much interest because of their optimized electronic structure, adjustable crystal phase, and abundant active site. The controlled tuning of the porous structure of TMBs, exploring the relationship between the structure and performance, and understanding the function of B are essential for developing catalysts with excellent performance; however, these factors have rarely been reviewed. Herein, a detailed summary of the synthesis methods of porous TMBs is provided by precisely defining their shape, composition, and pore size/structure. Incorporating B into metals can significantly alter their performance due to the unique metalloid properties of B. Further, we focus on the key roles of B in porous TMBs for related heterogeneous catalytic applications, including phase control, regulated electronic structure, optimized adsorption of reaction intermediates, and enhanced charge transfer and stability. Finally, we outline the shortcomings, challenges, and possible development of porous TMBs, which need to be further explored to increase TMBs' contribution to heterogeneous catalyst applications and beyond.

Stepwise Monomicelle Assembly for Highly Ordered Mesoporous TiO2 Membranes with Precisely Tailored Mesophase and Porosity

“…Certain strategies ( e.g. , sol–gel method, hydrothermal process, evaporation method) have been developed for creating well-defined crystalline mesoporous metals, − oxides, − and other compounds. − Unfortunately, the construction of crystalline mesoporous membranes/films currently remains a great challenge, and the precision control of mesoscale architectures, porous configurations, and mesoscopic parameters also remains far out of reach. , In this regard, the development or optimization of reliable strategies and comprehending of assembly chemistries of mesostructured crystalline membranes are quite imperative.…”

Introducing Porosity into Refractory Molybdenum Boride through Controlled Decomposition of a Metastable Mo–Al–B Precursor

“…Most synthetic routes to mesoporous metal borides use solution phase reduction of soluble reagents, which produces poorly crystalline or amorphous materials. 20,29 Methods that produce bulk quantities of mesoporous crystalline refractory metal borides do not exist despite the benefit of such a morphology on properties and applications.…”

“…Metal borides are an important class of refractory compound for the development of synthetic pathways to mesoporous products . Transition metal borides catalyze a wide range of chemical reactions, and mesoporosity is well known to enhance catalytic activity by increasing the surface area of the material, which increases the density of accessible active sites. − For example, α-MoB has been shown to be a highly active heterogeneous catalyst for the hydrogen evolution reaction (HER), which is the cathode reaction for overall water splitting. − Introducing mesoporosity into α-MoB, which is a refractory compound that is usually synthesized above 1000 °C in bulk, would provide a higher surface area to weight ratio.…”

“…Transition metal borides catalyze a wide range of chemical reactions, and mesoporosity is well known to enhance catalytic activity by increasing the surface area of the material, which increases the density of accessible active sites. − For example, α-MoB has been shown to be a highly active heterogeneous catalyst for the hydrogen evolution reaction (HER), which is the cathode reaction for overall water splitting. − Introducing mesoporosity into α-MoB, which is a refractory compound that is usually synthesized above 1000 °C in bulk, would provide a higher surface area to weight ratio. Most synthetic routes to mesoporous metal borides use solution phase reduction of soluble reagents, which produces poorly crystalline or amorphous materials. , Methods that produce bulk quantities of mesoporous crystalline refractory metal borides do not exist despite the benefit of such a morphology on properties and applications.…”

Functional Surfactant-Induced Long-Range Compressive Strain in Curved Ultrathin Nanodendrites Boosts Electrocatalysis

“…The design and synthesis of high-efficiency electrocatalysts have always been a crucial issue in the field of energy chemistry. − In the past decades, many innovative strategies have been developed to produce various electrocatalysts with desired performance, such as alloying with secondary metals and fabricating heterogeneous interfaces with transition metal dichalcogenides and carbon materials, − etc. Nevertheless, comprehensively considering the practical performance (activity and stability) and the cost of synthesis, noble metals catalysts remain the most utilized electrocatalysts in fuel cell .…”