Abstract Hydrogen energy is considered as promising renewable resource and desirable alternative to fossil fuels for future energy supply. Hydrogen production from electrocatalytic water splitting is a green and key approach for hydrogen energy development and application, and the effective electrocatalysts for hydrogen evolution reaction (HER) with low cost is the focus of ongoing research. Currently, noble metals‐based materials are the most effective and durable electrocatalysts for HER, while the high cost and low reserves greatly hinder their commercial applications. Recently, layered double hydroxides (LDHs) with interesting properties, such as the tunability of metal cation and interlayer anions, the adjustability of the thickness and spacing for the layers, low cost, and memory effect, have emerged as excellent electrocatalysts to enhance HER performance. Herein, the principal mechanisms and some key parameters for HER are firstly briefly introduced. Afterwards, the structural features and characteristics of LDHs are provided, and the typical design strategies to improve the HER activity of binary and ternary LDHs‐based catalysts are analyzed and discussed. In addition, the relationship between the morphology, structure, composition and involved electronic effects are focused and emphasized. Finally, the challenges and prospects of LDHs‐based catalysts for enhanced HER performance are proposed.
Ethanol as a fuel for direct ethanol fuel cells (DEFCs) has the advantages of being highly energetic, environmentally friendly, and low-cost, while the slow anodic ethanol oxidation reaction (EOR), intermediate poisoning effect, and incomplete oxidation of ethanol became obstacles to the development of DEFCs. Herein, a 2D ternary cyclic Pd3 Pt1 Rh0.1 nanorings (NRs) catalyst with efficient EOR performance is prepared via a facile one-pot solvothermal approach, and systematic studies are carried out to reveal the mechanisms of the enhanced performance and C-C bond selectivity. In particular, the optimized catalyst exhibits impressive mass activity, stability, toxicity resistance, and C-C bond cleavage ability. It's proposed that the considerable performance is attributed to the unique hollow structure, providing abundant active sites. The high toxicity resistance is not only attributed to the electronic modulation of the catalyst material by Rh atoms, but also depends on the excellent water activation properties of Rh, which contribute to the removal of intermediates, such as CO. In addition, the density functional theory calculations showed that the introduction of Rh significantly enhances the C-C bond cleavage ability of the catalyst, further improving the EOR activity.
Developing highly efficient electrocatalysts is yet an important challenge for water electrolysis. Herein, the in-situ growth of Co-doped NiSe2 on nickel foam (Co-NiSe2/NF) has been synthesized. Co-NiSe2/NF exhibited an overpotential of 136 mV at 10 mA cm−2 with a Tafel slope of 80.9 mV dec−1. In addition, the stability testing showed 92.4% of its initial HER activity after 60 h at 10 mA cm−2. The results showed that the introduction of Co tunes the electronic structure of Co-NiSe2/NF, resulting in fast reaction kinetics, and an enhanced stability due to the in situ growth of NiSe2 on the NF surface.
Abstract Both sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) are considered as promising candidates in grid‐level energy storage devices. Unfortunately, the larger ionic radii of K + and Na + induce poor diffusion kinetics and cycling stability of carbon anode materials. Pore structure regulation is an ideal strategy to promote the diffusion kinetics and cyclic stability of carbon materials by facilitating electrolyte infiltration, increasing the transport channels, and alleviating the volume change. However, traditional pore‐forming agent‐assisted methods considerably increase the difficulty of synthesis and limit practical applications of porous carbon materials. Herein, porous carbon materials (Ca‐PC/Na‐PC/K‐PC) with different pore structures have been prepared with gluconates as the precursors, and the amorphous structure, abundant micropores, and oxygen‐doping active sites endow the Ca‐PC anode with excellent potassium and sodium storage performance. For PIBs, the capacitive contribution ratio of Ca‐PC is 82% at 5.0 mV s −1 due to the introduction of micropores and high oxygen‐doping content, while a high reversible capacity of 121.4 mAh g −1 can be reached at 5 A g −1 after 2000 cycles. For SIBs, stable sodium storage capacity of 101.4 mAh g −1 can be achieved at 2 A g −1 after 8000 cycles with a very low decay rate of 0.65% for per cycle. This work may provide an avenue for the application of porous carbon materials in the energy storage field.
Microbial fuel cells (MFCs) can be capable of both wastewater treatment and electricity generation, which necessarily depends on the increasing cathodic performances and stability at low cost to realize industrialization. Herein, cellulose, a commercially available and sustainable material, was oxidized as a carbon precursor to produce the oxygen species synergizing the nitrogen-doped carbon (CON-900) catalyst by a facile in situ nitrogen doping method. The incorporation of nitrogen and oxygen with a high content creates more active centers. Meanwhile, the hierarchical porosity of CON-900 contributes to a high specific surface area (652 m2 g-1) and the exposure of accessible active sites. As expected, CON-900 exhibits considerable activity for the oxygen reduction reaction, excellent operating stability, and high poisoning resistance. In addition, the MFC fabricated with CON-900 as a cathode catalyst demonstrates a maximum power density of 1014 ± 23 mW m-2, which is comparable with that of the Pt/C cathode (1062 ± 14 mW m-2). This work offers a facile and versatile strategy for various biomass materials to develop low-cost and high-efficiency carbon-based catalysts for MFCs and beyond.
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