Covalently Connected Nb₄N_5–xO_x–MoS₂ Heterocatalysts with Desired Electron Density to Boost Hydrogen Evolution

Abstract

Rational design and controllable synthesis of efficient and robust electrocatalysts for hydrogen evolution reaction (HER) remain a critical challenge for the renewable energy economy. Herein, heterostructured Nb4N5–x O x –MoS2 (0 < x < 1) anchored on N-doped graphene (defined as Nb4N5–x O x –MoS2/NG) is synthesized by hydrothermal and chemical vapor deposition (CVD) approaches. During the CVD process, MoS2 nanosheets are etched into small pieces and covalently interconnected with Nb4N5–x O x to form fine Nb4N5–x O x –MoS2 heterostructures, which possess abundant interfaces and fully exposed edge active sites. The as-prepared Nb4N5–x O x –MoS2 heterostructures with Nb–(N,S)–Mo bridges provide desired electron density, which exhibit excellent chemisorption ability for both H and water, significantly improving the intrinsic HER activity. Meanwhile, the covalently connected Nb4N5–x O x –MoS2 heterostructures together with chemical coupling of Nb4N5–x O x –MoS2 and N-doped graphene improve the structural stability and ensure fast electron transfer in the Nb4N5–x O x –MoS2/NG nanocomposite, further supporting the H2 generation and stability.

Engineering Steam Induced Surface Oxygen Vacancy onto Ni–Fe Bimetallic Nanocomposite for CO2 Electroreduction

“…With a hydrothermal treatment, the well‐mixed precursor solution formed a homogeneous pillar, in which the metal ions were anchored onto the GO sheets. [ 21 ] Subsequently, the mixture was treated by a CVD process under NH 3 /Ar gas, and the resulting composite is denoted as NiFe/NG. Finally, NH 3 introduction stopped and H 2 through deionized water was introduced to the CVD tubes, and H‐NiFe/NG nanocomposites were synthesized by annealing with high temperature steam.…”

Valence Alignment of Mixed Ni–Fe Hydroxide Electrocatalysts through Preferential Templating on Graphene Edges for Enhanced Oxygen Evolution

“…The individual graphene nanosheet typically contains 3−10 layers at a thickness of 1−4 nm, with an approximate mass loading of 0.1 mg cm −2 . 13,34 Upon Ar plasma post-treatment, smaller and thinner graphene nanoflakes emanating from the backbone of pristine graphene nanosheets were observed (Figure S1b), forming the hierarchical edge-rich structure (i.e., er-VG) with an increased packing density (the cavity size was reduced slightly to 0.1−0.4 μm). Nevertheless, er-VG still maintained the open and interconnected structure of pristine VG which resulted in an increased surface area of approximately 1.5 times compared to that of VG (Figure S2).…”

“…Furthermore, the extended graphene edge planes, which may be systematically tuned, have been shown to have a distinct edge-state with defined electronic properties . It has been demonstrated that a highly available density of states and charge localization through an extended π-bonding/antibonding system can give rise to a unique chemical reactivity, affecting the interactions of other chemical moieties on the edge planes. − These edge sites are therefore able to alter the interaction between the supporting graphene and active metal, changing the local coordination environment, and thus modulating the valence states of metal species. ,, In general, control of these valence states is intrinsically important to tune the catalytic performance of metals, as they define the adsorbate energy of intermediate species and therefore the catalytic performance. − Despite this progress, the understanding and application of graphene edges in improving the electrocatalytic performance of metal catalysts remain elusive in the recent literature.…”

Boosting pH‐Universal Hydrogen Evolution of Molybdenum Disulfide Particles by Interfacial Engineering†

“…[ 11‐14 ] Yet, the extremely high price and scarcity of Pt‐based catalysts on Earth limit its scalable application. Thus, considerable efforts have been devoted to looking for cheap and efficient catalysts made of cheap materials, [ 15‐20 ] including metal phosphides, sulfides, selenides, MXenes, and so forth. As a new emerging two‐dimensional material produced in 2011, MXenes have attracted considerable attention for electrocatalysis, Li‐based batteries or supercapacitors due to their inherent metallic character and hydrophilic surfaces.…”