Borophene as a prototype for synthetic 2D materials development

Abstract

The synthesis of 2D materials with no analogous bulk layered allotropes promises a substantial breadth of physical and chemical properties through the diverse structural options afforded by substrate-dependent epitaxy. However, despite the joint theoretical and experimental efforts to guide materials discovery, successful demonstrations of synthetic 2D materials have been rare. The recent synthesis of 2D boron polymorphs (that is, borophene) provides a notable example of such success. In this Perspective, we discuss recent progress and future opportunities for borophene research. Borophene combines unique mechanical properties with anisotropic metallicity, which complements the canon of conventional 2D materials. The multi-centre characteristics of boron-boron bonding lead to the formation of configurationally varied, vacancy-mediated structural motifs, providing unprecedented diversity in a mono-elemental 2D system with potential for electronic applications, chemical functionalization, materials synthesis and complex heterostructures. With its foundations in computationally guided synthesis, borophene can serve as a prototype for ongoing efforts to discover and exploit synthetic 2D materials.

Nickel‐Based Transition Metal Nitride Electrocatalysts for the Oxygen Evolution Reaction

“…[29,83,84] Some Ni-basedt ernary nitrides (bimetallic nitrides)o ffer improved activity in overall water splitting procedures comparedt ot he single metal nitrides, as the introduction of the second metal strongly affects the arrangement of atoms to afford more favorable electronic properties. For example,N ickel-iron, [55,77,78,82] nickel-cobalt, [53,55] nickel-manganese, [55] and nickel-molybdenum [54,81] nitrides have been reported as potentialO ER electrocatalysts with applications for half-cell reactions in water splitting. These ternary nitrides are mostly also active for the HER, [55,77,78,82] so they are applicable as both cathode and anode electrocatalysts for overall H 2 O electrolysis.…”

“…For example,N ickel-iron, [55,77,78,82] nickel-cobalt, [53,55] nickel-manganese, [55] and nickel-molybdenum [54,81] nitrides have been reported as potentialO ER electrocatalysts with applications for half-cell reactions in water splitting. These ternary nitrides are mostly also active for the HER, [55,77,78,82] so they are applicable as both cathode and anode electrocatalysts for overall H 2 O electrolysis. These aforementioned ternary nitrides as bifunctional catalysts are reported in detail in many of the research articles summarized in this Minireview.…”

Beneficial impact of materials with reduced dimensionality on the stability of perovskite-based photovoltaics

“…Even though the oxidation process appears to be limited to its edges, it can certainly interfere with the charge distribution over the layer. Nonetheless, borophene being a highly conductive medium opens possibilities for application in conjunction with boron nitride or other previously mentioned 2D materials, which are able to act as a shield from the negative ambient influences [40]. Additional research efforts should be directed towards design of scalable and standardized solution processing fabrication methods for 2D materials applicable to perovskite photovoltaics, without sacrificing photoconversion efficiency and overcomplicating device design.…”

Thermodynamic stability of borophene, B2O3 and other B1−xOx sheets

“…The experimental discovery of this 'borophene' was anticipated by various theoretical predictions ranging back to the mid-1990s [5][6][7][8]. Analogous to the existence of many boron bulk phases, free-standing borophene exhibits a pronounced polymorphism [7,9]; however it is lifted in the vicinity of a metal surface which enables the growth of specific borophene crystals [10,11]. A prototypical borophene (the α′-sheet) is shown in figure 1(a).…”

“…Several authors theoretically studied the adsorption of oxygen on the buckled triangular borophene [28][29][30][31] or related nanoribbons [32]. However, structures related to the buckled triangular structure are not thermodynamically favorable neither as stand-alone system nor when placed on a metal surface [11] and angle-resolved photoemission spectroscopy of the experimentally realized borophenes (β 12 and χ 3 sheets) are also highly consistent with non-triangular borophenes [33,34]. A different theoretical study was performed by Luo et al who considered oxygen adsorption, dissociation and diffusion on χ 3 borophene on Ag(111) [35].…”