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[Display omitted] • Both ion-sharing interface and directional doping are employed to construct a heterostructured HER electro-catalyst. • Electronic structure and coordination chemistry of Mo and Co centers are tailored to optimize adsorption/desorption of H ads and OH– intermediates for lowering the energy barriers. • Mo center with more coordination vacancies are main active sites responsible for rate-limiting step in the Volmer-Heyrovsky regime. • This catalyst presents an extremely low overpotential of 37 mV at 10 mA cm−2 in alkaline media, and excellent performance for overall water splitting. Interfacing and doping can effectively harmonize the electronic and coordination states of active centers in the electrocatalysts. Herein, we prepare heterostructured N-MoS 2 /Se-CoS 2 electrocatalyst with ion-sharing interfaces and directional doping to activate inert basal phases for hydrogen evolution reaction (HER). Based on experimental and theoretical results, their synergistic effects on electron redistribution, electronic structure and coordination chemistry are investigated; furthermore, roles of each component and bridged Mo-S-Co sites at the phase interfaces as active sites in optimizing the adsorption/desorption of essential reaction intermediates H* and OH–, as well as the free energies of unit reaction steps in the HER, are elucidated in depth. The N-MoS 2 /Se-CoS 2 catalyst needs only 37 mV to give current density of 10 mA cm−2 with a low Tafel slope of 49.4 mV dec−1; more importantly, the catalyst delivers a long-term durability for HER in alkaline condition and comparable performance with commercial RuO 2|| Pt/C system in a two-electrode assembled electrolyzer. This work provides more insights into the design and preparation of high-performance heterostructured electrocatalysts. [ABSTRACT FROM AUTHOR]

Pyrolytic reforming of toluene over Ni-based catalysts loaded on nano-sized and micro-sized γ-Al 2 O 3 is investigated in a fixed bed reactor under the temperature from 500 °C to 800 °C. The physicochemical properties of γ-Al 2 O 3 and Ni/Al 2 O 3 catalysts were characterized by HRTEM, XPS, XRD and H 2 -pulse chemisorption. The metal Ni loaded on micro-sized γ-Al 2 O 3 gave the steady toluene conversion of more than 80% and graphite yield of 87.3% after 1 h of reforming reaction. The rapid decrease of H 2 yield from 5.2 mmol/g-toluene to 0.4 mmol/g-toluene over Ni/nano-Al 2 O 3 was obtained during the 1 h of reforming reaction at 500 °C. The particle size of metal Ni over nano-sized and micro-sized γ-Al 2 O 3 were centered at 7.8 nm and 28.8 nm, respectively. The metastable NiC x crystallites were observed over the spent Ni/nano-Al 2 O 3 catalyst, while only metal Ni were obtained over the spent Ni/micro-Al 2 O 3 catalyst. Ni0+ particle size-dependent crystalline phase was evidenced by MD simulations, where incorporation of more carbon atoms was achieved on small Ni particles. The energy barrier for –CH 2 dehydrogenation over Ni 32 C, Ni 4 C and Ni 3 C were estimated to be 90.2, 105.1 and 116.0 kJ/mol through the DFT simulation, respectively. It can be concluded that the crystalline Ni phase was maintained over Ni/micro-Al 2 O 3 with large Ni particle size, prolonging the catalytic endurance and promoting the CNTs (Carbon Nanotubes) growth without the deposition of unexpected amorphous carbon. • The influence of γ-Al 2 O 3 on Ni/Al 2 O 3 catalytic reforming performance was investigated. • Ni0+ particle size-dependent pyrolytic reforming for co-production of H 2 and CNTs was revealed. • The carbon solubility on Ni particles with different sizes was simulated. [ABSTRACT FROM AUTHOR]