A highly active and stable electrochemical catalyst of nanoporous molybdenum carbide nanowires (np-Mo₂C NWs) has been developed for hydrogen evolution reaction (HER). The np-Mo₂C NWs were synthesized simply by pyrolysis of a MoO_x/amine hybrid precursor with sub-nanosized periodic structure under an inert atmosphere. The enriched nanoporosity and large reactive surface of these highly dispersed nanowires with uniform Mo₂C nanocrystallites provide an efficient electrocatalysis, leading to their superior HER activity with lower onset overpotential and higher current densities than Mo₂C microparticles. This study opens a new perspective for the development of highly active non-noble electrocatalysts for hydrogen production from water splitting.

Electronic regulation of Mo₂C and thus intrinsically improved HER activity via balanced Volmer and Heyrovsky/Tafel steps.

Zeolites with hierarchically porous structures have garnered much attention due to their highly attractive properties. Hierarchically structured zeolites integrate at least two levels of porosity and present the advantages associated with each level of porosity, from selectivity to mass transport. They are categorized into three distinctly different types according to their hierarchical porosities: mesostructured zeolites, macrostructured zeolites, and micro–meso–macroporous structured zeolites. Most importantly, hierarchically structured zeolites offer an effective solution to the mass transport problem associated with conventional zeolites in catalysed reactions because they combine the catalytic features of micropores and the improved accessibility and increased molecular transport related to the addition of several porosities within a single body. In recent years, many strategies have been successfully developed to synthesize hierarchically structured zeolitic materials. This feature article thoroughly summarizes recent developments that have been achieved in the field of hierarchically structured zeolites, with the main focus on the synthesis strategies that are available, with examples given from the literature. Available approaches are reviewed for the preparation of micro–mesoporous structured zeolites, micro–macroporous structured zeolites and micro–meso–macroporous structured zeolites. Furthermore, the enhanced mass transport properties of hierarchically structured zeolites, featuring additional larger pores in addition to the crystalline micropores, have also been described. The significant improvement in catalytic properties in a range of important reactions resulting from enhanced mass transport properties have also been discussed through several representative cases. It is the intent of this work to stimulate intuition into the optimal design of related hierarchically organized zeolites with desired characteristics.

The hydrogen evolution reaction using noble-metal free electrocatalysts has captured increasing attention due to its importance in renewable hydrogen production. Herein, a highly active and stable electrocatalyst of MoC encapsulated by graphitized carbon shells (nanoMoC@GS) has been developed via an in situ carburization of a Mo-based metal–organic framework (Mo-MOF) with the atomic periodic structure. The ultrafine MoC nanoparticles (∼3 nm) confined by 1–3 layered graphite shells significantly favor the efficient HER in both acidic and basic media. In particular, a low overpotential (η₁₀ = 124 and 77 mV at a current density of −10 mA cm⁻²), a small Tafel slope (43 and 50 mV dec⁻¹) and a high exchange current density (j₀ = 0.015 and 0.212 mA cm⁻²) are achieved on nanoMoC@GS in 0.5 M H₂SO₄ and 1.0 M KOH, respectively. Such remarkable activity, outperforming most current noble-metal-free electrocatalysts, stems from the cooperative/synergistic effects of ultrafine MoC nanostructure, ultrathin and conductive graphitized carbon shells, and enriched porosity. This work demonstrates a feasible way to design high-performance electrocatalysts via converting “atomic contact” hybrid structures (e.g., MOFs), illustrating a new perspective for developing nanocatalysts in the energy chemistry field.