Surface and Interface Engineering: Molybdenum Carbide–Based Nanomaterials for Electrochemical Energy Conversion

Abstract

Molybdenum carbide (MoxC)‐based nanomaterials have shown competitive performances for energy conversion applications based on their unique physicochemical properties. A large surface area and proper surface atomic configuration are essential to explore potentiality of MoxC in electrochemical applications. Although considerable efforts are made on the development of advanced MoxC‐based catalysts for energy conversion with high efficiency and stability, some urgent issues, such as low electronic conductivity, low catalytic efficiency, and structural instability, have to be resolved in accordance with their application environments. Surface and interface engineering have shown bright prospects to construct highly efficient MoxC‐based electrocatalysts for energy conversion including the hydrogen evolution reaction, oxygen evolution reaction, nitrogen reduction reaction, and carbon dioxide reduction reaction. In this Review, the recent progresses in terms of surface and interface engineering of MoxC‐based electrocatalytic materials are summarized, including the increased number of active sites by decreasing the particle size or introducing porous or hierarchical structures and surface modification by introducing heteroatom(s), defects, carbon materials, and others electronic conductive species. Finally, the challenges and prospects for energy conversion on MoxC‐based nanomaterials are discussed in terms of key performance parameters for the catalytic performance.

Self‐Assembled Ruddlesden–Popper/Perovskite Hybrid with Lattice‐Oxygen Activation as a Superior Oxygen Evolution Electrocatalyst

“…On the one hand, the interface can serve as new catalytic actives with the optimized electronic structure through the existence of charge transfer and lattice stress between the multiple compounds. [ 30–33 ] On the other hand, the hybrid systems can induce some synergetic effects enabling to stabilize catalytic sites, and achieve a desirable electrocatalytic stability. [ 34,35 ] Therefore, we believe that the formation of RP/perovskite hybrid may be a viable way to regulate the electronic structure and accordingly boost the electrocatalytic performance.…”

Melamine-assisted synthesis of ultrafine Mo2C/Mo2N@N-doped carbon nanofibers for enhanced alkaline hydrogen evolution reaction activity

“…Thus, the development of Mo 2 Cor Mo 2 N-based electrocatalysts with enhanced catalytic activity for HER in alkaline solution is highly imperative. Nevertheless, the traditional synthesis methods of Mo 2 C or Mo 2 N always suffer from excessive growth and aggregation at high temperatures, which lead to the low utilization of catalysts [13,[20][21][22]. To date, the main effective strategy is compositing nanostructured Mo 2 C or Mo 2 N with carbon substrate to increase edge-sites and electronic conductivity [23][24][25][26].…”

“…And the intrinsic electrocatalytic activity of MoO x in HER is inferior to that of Mo 2 C as a candidate component to construct the heterostructure. As same as Mo 2 C, Mo 2 N possesses Pt-resembled d-band density, which makes the synthesis of Mo 2 C/Mo 2 N heterostructure attractive [12][13][14]. However, the construction of ultrafine molybdenum carbide/nitride heterostructure within nitrogen-rich carbon is difficult and has rarely been reported up to now.…”

“…3h) confirms that two sides of the interface are the fringes corresponding to the (101) plane of Mo 2 C and the (112) plane of Mo 2 N, respectively. The interface always induces the optimization of electronic configuration and adsorption free energy through the interfacial electron transfer through heterointerfaces, achieving synergistic effect to improve electrocatalytic activity [13,37]. Fig.…”

“…Transition metal compounds have been widely studied as electrocatalysts for HER in recent years [10,11]. Among these compounds, Mo 2 C and Mo 2 N are outstanding due to their similar d-band density with Pt, good hydrophilia and chemical stability [12][13][14], hence, arising concentrated interests. For example, NiO/β-Mo 2 C/reduced graphene oxide (RGO) [15], α-MoC [16], and Mo 2 C-Mo 3 C 2 [17] were synthesized and employed as electrocatalysts to achieve high HER performance.…”