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[Display omitted] • Carbon confined iron-nickel alloy/iron fluoride doped by oxygen derived from nano rod-like Fe 2 Ni MIL MOF. • Structural transformation demonstrated by spectroscopic analysis was correlated to electrochemical catalytic performance. • C/O-FeNi/FeF 2 exhibited high catalytic activity and stability for OER with faster charge transfer ability. • High activity comes from carbon confined active phase, increased polarity, strong electronic effect and efficient synergism. Carbon confined active phase plays a significant role in the novel catalyst materials development and fabrication. Herein, we demonstrate such a catalyst material in the form of carbon confined iron-nickel alloy/iron fluoride doped by oxygen (C/O-FeNi/FeF 2) derived from the Fe 2 Ni MIL MOF via facile carbonization and fluorination for efficient oxygen evolution reaction (OER) in the water-splitting reaction. The structural transformation from the Fe 2 Ni MIL MOF to the C/O-FeNi/FeF 2 is demonstrated by the spectroscopic analysis and correlated to their electrochemical catalytic performance. Because of some combined merits resulting from the carbon confined active phase, increased polarity, strong electronic effect and efficient synergism of metal and metal fluoride for the facile active phase reconstruction in this hybrid system, this catalyst exhibits many good characteristics for electrochemical measurements in terms of improved conductivity, high intrinsic activity and stability, fast catalytic kinetics, increase surface area and rapid charge transfer ability. Specifically, the C/O-FeNi/FeF 2 catalysts have a low overpotential of ca. 250 mV when loaded on a glass carbon electrode to offer the current density of 10 mA cm−2 in the alkaline electrolyte for OER; and no obvious performance decay is observed in the long-term stability test conducted at different potentials. The current results will be instructive for novel carbon confined catalyst and MOF derived catalyst design and fabrication in the energy catalysis reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Activity of CoFe 2 O 4 boosted by hybrid structure engineering and fluorine doping. • Fluorine doping-induced charge redistribution and accelerating CoOOH formation. • Stable F incorporation enhanced OER kinetics and catalytic activity. • CoOOH active layer formed over the F-CoFe2O4 surface was active for OER. CoFe 2 O 4 is a very promising platform to catalyze oxygen evolution reaction (OER). Herein, the largely enhanced intrinsic performance of CoFe 2 O 4 derived from the ZIF-67 for OER was demonstrated by step-by-step hybrid structure engineering and fluorine doping (F-Co/CoFe 2 O 4 @NC). This electrode showed high surface area, rapid charge transfer ability, and catalytic kinetics compared to the CoFe 2 O 4 @NC and Co/CoFe 2 O 4 @NC catalysts. Specifically, an overpotential of 280 mV was required to drive a kinetic current density of 10 mA cm−2 (loading on glassy carbon electrode, no iR-correction), with a Tafel slope of 49.7 mV dec-1 and remarkable catalytic stability throughout a 50-hour test. Theoretical analysis revealed a charge redistribution among Co, and Fe atoms was triggered by fluorine doping, and a more rapid active phase of CoOOH was generated on the surface during catalysis as confirmed by in-situ Raman spectroscopy and the post-surface chemical state analysis. The stable F atoms were more likely to be doped into CoFe 2 O 4 , and the active layer of CoOOH formed over the F-CoFe 2 O 4 surface was more active than other states. Moreover, the electronic interaction induced by F-doping is more conducive to improving the adsorption energy of *OOH species, thereby improving the reaction kinetics and catalytic activity of OER. The current work showed an effective step-by-step approach to boosting the intrinsic activity of traditional catalysts for energy-relevant catalysis reactions. [ABSTRACT FROM AUTHOR]

Herein, we demonstrated that a novel derivative of zeolitic imidazolate framework (ZIF) obtained by direct fluorination (ZIF-67) is an efficient electrocatalyst for Oxygen Evolution Reaction (OER). The obtained catalyst showed the main phase of tetragonal CoF 2 from the metal center and the nitrogen-doped carbon from the ligands of ZIF-67. The polyhedral morphology was well kept but with a more rough surface consisting of assembled nanoparticles. Due to the good conductivity and high polarity in the system, this electrocatalyst showed an overpotential of 294 mV required to yield 10 mA cm−2 with good stability. [Display omitted] • ZIF-67 derived cobalt fluoride is active for oxygen evolution reaction. • The structure of N-doped carbon can increase the conductivity of the catalyst. • The obtained CoF 2 from the metal center has high polarity. • Extending the application of the novel derivative by direct fluorination of MOF-based materials. [ABSTRACT FROM AUTHOR]

Support engineering modulated Pt by hierarchical MoSe 2 @mesoporous hollow carbon support well addressed the challenges in low intrinsic activity and easy poisoning problems during methanol electrolysis. [Display omitted] • Electrochemical energy conversion from methanol to hydrogen via methanol electrolysis. • Support engineering modulated Pt by hierarchical MoSe 2 @mesoporous hollow carbon support. • Strong interaction and coupling ability between Pt and MoSe 2 regulated the active centers. • Weakened binding strength of CO ad and H ad intermediates during catalysis. • High electrochemical properties due to enhanced oxophilicity and poisoning tolerance ability. Hydrogen generation from methanol via methanol-assisted water splitting is a promising electrochemical energy conversion technology but still meets challenges in addressing the low intrinsic activity and easy poisoning problems of the conventional Pt catalysts. Herein, the support engineering modulated Pt by hierarchical MoSe 2 @mesoporous hollow carbon support was proposed to integrate some structural and catalytic advantages for hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR). Supporting engineering by layered MoSe 2 nanosheets confined in mesoporous hollow carbon spheres (MHCSs) is adopted to uniformly anchor Pt nanoparticles (Pt/MoSe 2 @MHCS), which effectively enhances the conductivity and prevents the layer-by-layer stacking of MoSe 2 ; Strong interaction and coupling ability between Pt and MoSe 2 and the resultant electronic structure regulation of the active centers could weaken the binding strength of CO* and H* intermediates during catalysis and strengthen the oxophilicity leading to improved MOR and HER kinetics. Specifically, Pt/MoSe 2 @MHCS shows a significantly improved MOR current density of 81.1 mA cm−2, about 3.0 times that of the benchmark Pt/C catalyst. Meanwhile, it also exhibits the HER performance of 28 mV to achieve a kinetic current density of 10 mA cm−2 in methanol-contained electrolytes. When employed for overall methanol electrolysis, a lowered input voltage of 1.11 V can be obtained to drive the current density (10 mA cm−2) compared to that for water electrolysis (0.62 V vs. 1.73 V). The electrochemical properties of high activity, rapid catalytic kinetics, and good stability were also demonstrated due to the enhanced oxophilicity and high poisoning tolerance ability resulting from the MoSe 2 /carbon substrate-induced electron redistribution of Pt sites. This work reports a novel platform to address the catalysis challenges in hydrogen production via the methanol electrolysis technique. [ABSTRACT FROM AUTHOR]