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Electrochemical water splitting is one of the most economical and sustainable methods for large-scale hydrogen production. However, the development of earth-abundant non-noble-metal catalysts toward hydrogen evolution reaction, with excellent activity and stability, remains a great challenge. In this work, the coupled hybrids of β-Mo 2 C nanoparticles and porous N -doped carbon nanoplates is successfully constructed by the one-pot solution-free strategy. The hybrids exhibits high electrocatalytic activity for hydrogen evolution reaction with a small overpotential of 116 mV and 187 mV to deliver a current density of 10 mA/cm2 in 1.0 M KOH and 0.5 M H 2 SO 4 solution. Furthermore, the hybrids have excellent stability in not only acidic solutions but also basic solutions. The superior activity and remarkable stability originated from the N -doped carbon nanoplates supplying enough surface area, the ultrafine β-Mo 2 C nanoparticles providing sufficient electrocatalytic active sites, the mesoporous structure facilitating the charge/mass transportation, and the coupling effect dropping the adsorption free energy of hydrogen. This work presents a simple and effective approach to prepare molybdenum-based materials with excellent electrocatalytic performance for hydrogen production. Image 1 [ABSTRACT FROM AUTHOR]

• Fe-doped α-MoO 3 nanoarrays was first synthesized by a simplistic solid-state chemical reaction strategy. • Fe-doped MoO 3 nanoarrays exhibited a high response. • The high response originated from more internal oxygen vacancies and surface ionized oxygen species. • The nanoarrays have also excellent selectivity, rapid response-recovery and good long-term stability. Fe-doped α-MoO 3 nanoarrays have been synthesized via a facile two-step solid-state chemical reaction process. The Fe element was effectively doped into the α-MoO 3 nanoarrays self-assembled by nanoplates via an initial room-temperature solid-state reaction and a subsequent mesothermal calcination. The gas-sensing properties of Fe-doped α-MoO 3 nanoarrays were investigated and the possibility of its application to gas sensors was explored. The result indicated that 0.3 mol% Fe-doped α-MoO 3 nanoarrays exhibited a high response value (28.5) towards 100 ppm xylene within 2 s, which is attributed to its more oxygen vacancies and surface ionized oxygen species. Furthermore, the 0.3 mol% Fe-doped α-MoO 3 nanoarrays also manifested a good selectivity and long-term stability. Therefore, the Fe-doped MoO 3 nanoarrays are a potential candidate for xylene sensor in future sensing applications. [ABSTRACT FROM AUTHOR]

The Ag 2 O/Ag 2 CO 3 heterostructure photocatalysts synthesized and regulated using simple one-step solid-state chemical process at room temperature exhibited outstanding visible light-driven photocatalytic acivity. • The heterojunction were in situ constructed by one-step room temperature solid-state method. • The composition of heterojunction can be in situ regulated by solid-state method. • The regulation mechanism of heterojunction has also been revealed. • The obtained Ag 2 O/Ag 2 CO 3 displays outstanding photocatalytic activity and reusability. Ag-based photocatalysts have excellent photocatalytic properties, but their photocatalytic degradation performance is limited by the serious photocatalytic corrosion. In order to enhance the stability of photocatalytic degradation of Ag-based photocatalysts, here, the Ag 2 O/Ag 2 CO 3 heterojunction was in-situ constructed and conveniently regulated by controlling the alkalinity of room temperature solid-state chemical reaction system. The photocatalytic degradation activity of the obtained heterojunction was influenced by the in-situ regulated component and band position of the Ag 2 O/Ag 2 CO 3 heterojunction. The obtained optimal products AAC-6 displayed remarkable photocatalytic activity and high reusability. The apparent rate constant of AAC-6 is 20 times than that of Ag 2 CO 3 , it is also far higher than that of P25. The significantly enhanced photocatalytic performance can be ascribed to the matching energy position between Ag 2 CO 3 and Ag 2 O, which can facilitate the visible light absorption ability and the efficient separation of photoinduced charges carriers. This study explored an in-situ one-step solid-state strategy to construct Ag 2 CO 3 -based heterojunction catalyst with outstanding photocatalytic performance, which may open a new perspective for the preparation of excellent photocatalytic degradation materials by solid-state chemical method. [ABSTRACT FROM AUTHOR]

Graphical abstract The β-NiMoO 4 nanomrods were successfully fabricated by a green solid-state chemical approach and exhibit high electrochemical performance for supercapacitors. Abstract Simple solid-state chemical reaction was adopted to synthesize NiMoO 4 nanomaterials with different crystal phase without the use of organic solvent or templating agent. The as-prepared NiMoO 4 ·xH 2 O, α-NiMoO 4 and β-NiMoO 4 nanostructures were investigated as the electrode materials for supercapacitors. The β-NiMoO 4 nanorods were composed of the nanoparticles, which exhibited relatively high specific capacitances about 1415 F g−1 at a charge density of 1 A g−1, 80.2% of the initial reversible capacity was maintained after 1000 cycles. The β-NiMoO 4 //rGO asymmetric supercapacitor (ASC) system was assembled in serials, which displayed high specific energy density of 29.3 Wh kg−1 at a high power density of 187 W kg−1. This ASC system can drive the light-emitting diode (LED) effectively and give out light about 40 min, even easily light two LEDs in serials for 20 min. The remarkable electrochemical performances make the as-prepared NiMoO 4 nanostructures an excellent candidate as electrode materials for advanced supercapacitors. [ABSTRACT FROM AUTHOR]

To develop a low-cost and high-efficient electrocatalyst as a substitution of Pt/C for oxygen reduction reaction (ORR) is of great significance. We propose simple "two-pronged" strategy to boost synchronously the electrocatalytic activity and stability via the combination of the active MnO and metallic Ni with the conductive N-doped carbon (N–C) materials. The synergistic effect of active species between MnO and metallic Ni enables Ni–MnO/N–C composites to motivate-boost catalytic activity, the N–C greatly enhances the conductivity and endows Ni–MnO/N–C composites with large surface area for ORR. To our satisfaction, the Ni–MnO/N–C composites exhibits robust electrocatalytic ORR activity with the limiting current density (J) of 6.39 mA cm−2, the half-wave potential (E 1/2) of 0.81 V vs. RHE and an ideal four-electron transfer pathway, competing to the commercial Pt/C. Furthermore, the Ni–MnO/N–C composites as a cathode in assembled Zn-air battery shows the power density of 179 mW cm−2, delivers the specific capacity of 702 mA h g−1 at a discharge current density of 10 mA cm−2 while utilizing 84% of the theoretical capacity (~835 mA h g−1). This work highlights a new feasible strategy to explore an efficient electrocatalyst via synchronously heightening the catalytic activity and conductivity. • Proposed two-pronged strategy concurrently boosts activity and conductivity. • Solid-state technique is performed to prepare rod-like Ni–MnO/N–C composites. • Synergistic effect between active MnO and Ni motivates catalytic activity. • Ni–MnO/N–C shows superior activity in ORR and ZAB, competing to commercial Pt/C. [ABSTRACT FROM AUTHOR]