Effective C−C bond cleavage is a critical concern in the applications of ethanol technologies. The lack of catalytic efficiency toward complete ethanol oxidation reaction (EOR) has hindered the development of direct ethanol fuel cells. Ir-based catalysts have recently shown promise in the complete EOR. However, its catalytic mechanism remains unclear, which impedes the development of better Ir-based catalysts. Herein, we report a comprehensive reaction network of complete ethanol decomposition on Ir(100) based on the extensive density functional theory calculations. Our results show that decomposition of ethanol on Ir(100) consists of four sequential dehydrogenation steps that lead to the generation of CH 2 CO species then follows two competitive reaction pathways, namely, the C−O bond cleavage that leads to the formation of poisonous CHC species and the diffusion of CH 2 CO leading to complete oxidation:Furthermore, the formation of acetic acid is not favored on Ir(100). This work highlights the essential roles of adsorption structure and diffusion of CH 2 CO in ethanol decomposition and will serve as a benchmark for future investigation of the complete EOR, such as exploring the electric and solvent effects on EOR.

Synthesis of the electrode materials of sodiumion storage devices from sustainable precursors via green methods is highly desirable. In this work, we fabricated a unique N, O dual-doped biocarbon nanosheet with hierarchical porosity by direct pyrolysis of low-cost cuttlebones and simple air oxidation activation (AOA) technique. With prolonging AOA time, thickness of the carbon sheets could be reduced controllably (from 35 to 5 nm), which may lead to tunable preparation of carbon nanosheets with a certain thickness. Besides, an unexpected increase in N-doping amount from 7.5 to 13.9 atom % was observed after AOA, demonstrating the unique role of AOA in tuning the doped heteroatoms of carbon matrix. This was also the first example of increasing N-doping content in carbons by treatment in air. More importantly, by optimizing the thickness of carbon sheets and heteroatom doping via AOA, superior sodium capacity−cycling retention−rate capability combinations were achieved. Specifically, a current state-of-the-art Na + storage capacity of 640 mAh g −1 was obtained, which was comparable with the lithium-ion storage in carbon materials. Even after charging/discharging at large current densities (2 and 10 A g −1 ) for 10 000 cycles, the as-obtained samples still retained the capacities of 270 and 138 mAh g −1 , respectively, with more than 90% retention. The assembled sodium-ion capacitors also delivered a high integrated energy− power density (36 kW h kg −1 at an ultrahigh power density of 53 000 W kg −1 ) and good cycling stability (90.5% of capacitance retention after 8000 cycles at 5 A g −1 ).

A naturally fibrous carbon foam is fabricated by employing fish bones as raw materials. Differing to carbon foams in previous reports, numerous unwoven and crosslinked carbon nanofibers were found to construct the whole foam, exhibiting a hierarchical porosity with interconnected channels and multisize pores. In the meantime, on the basis of the rich organic−inorganic components of fish bones, an N-S-P-O codoping was achieved in carbon foams. Benefiting from the synergistic effects of hierarchically porous fibrous foam and multiple heteroatom doping, the as-obtained samples were employed both as anode and cathode materials in lithium ion hybrid supercapacitors (LIHC), which delivered a superior energy density of 131 Wh kg −1 in 0−4.0 V. Significantly, at an impressive power density of 62000 W kg −1 , the energy density of this device can still reach an ultrahigh energy density of 72 Wh kg −1 , which presents a state of the art supercapacitors. More importantly, continuously being charged/discharged at a high current density of 5 A g −1 for 20000 cycles, the LIHC device can still retain a high energy density of 79 Wh kg −1 with 82% retention, demonstrating the promising prospect of heteroatom doped fibrous carbon foam in high-performance hybrid supercapacitors.

A lack of comprehensive studies of the C–C bond cleavage in organic molecules hampers the rational design of catalysts for many applications, such as in fuel cells and steam reforming technologies. Employing ethanol on Ir(100) as an example, we studied 14 C–C bond cleavages of various species involved in the ethanol oxidation reaction using density functional theory calculations and used the degree of dehydrogenation (DoDH) of the reactant species as a variable to correlate the C–C bond cleavage barrier and reaction energy. This correlation method was also applied to the dehydrogenation reactions of ethanol on various catalysts, and great insight was obtained. The results show that the C–C cleavage barrier generally decreases with DoDH, with a local minimum around 33.3% DoDH. For reactants having more than 50% DoDH, the C–C cleavage is more ready to take place than the dehydrogenation and can occur at room temperature. Furthermore, the O atom in the reactive species plays a critical role in lowering the C–C bond cleavage barrier. The results provide necessary inputs for kinetic studies of ethanol reactions under operando conditions, where a reaction network beyond the minimum energy pathway is needed. The results will also serve as a benchmark for future studies of the ethanol C–C cleavage on other facets of Ir catalysts or on different catalysts. Furthermore, this work demonstrates that the proposed method opens up a new and effective way of correlating catalytic activities for the C–C bond cleavage involving long-chain alkanes and alcohols.

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