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Abstract As an excellent free-standing carbon source, commercialized cotton cloth can be carbonized to fabricate conductive carbon cloth composed of hollow carbon microfibers. In view of the hydrophobicity of carbon cloth, a functionalized carbonized cotton cloth (FCC) is prepared by acidification treatment, and acted as a flexible substrate to grow hierarchical SnO 2 nanoclusters by a solvothermal reaction and calcination process. In this SnO 2 wrapped FCC (FCC@SnO 2) composite, the oxygen-containing groups in carbon microfibers provide numerous anchoring sites for growing SnO 2 nanoparticles, meanwhile, the carbon microfibers provide conductive channels for the fast transfer of electrons and ions. The SnO 2 nanoclusters effectively contribute their pseudocapacitance. As free-standing electrodes in a symmetrical two-electrode supercapacitor, the FCC@SnO 2 composite exhibits a higher capacitance of 197.7 F g−1 or 1265.3 mF cm−2 at 1 A g−1, much higher than that of FCC (100.3 F g−1 or 411.2 mF cm−2); furthermore, its capacitance remains 95.5% after cycling for 5000 cycles at 15 A g−1. The FCC@SnO 2 composite is easier preparation and low cost, which can be utilized as self-supporting flexible electrodes for high performance supercapacitors. Graphical abstract Image 1 Highlights • Acidified carbonized cotton cloth is acted as a freestanding flexible substrate. • Hierarchical SnO 2 nanoclusters are wrapping on the surface of carbon microfibers. • FCC@SnO 2 exhibits a capacitance of 197.7 F g−1 or 1265.3 mF cm−2 at 1 A g−1. • Its capacitance retains 95.5% after cycling for 5000 cycles at 15 A g−1. [ABSTRACT FROM AUTHOR]

Cobalt disulfide (CoS 2 ) has been revealed as strong adsorption and activation sites for polar polysulfides, which effectively accelerates the redox reactions of polysulfides in lithium-sulfur (Li-S) batteries. As an ideal sulfur host, a three-dimensional (3D) graphene framework is adopted for high-performance Li-S batteries. Considering the special function of the CoS 2 nanoparticles and the advantages of a 3D porous graphene framework, a porous CoS 2 /reduced graphene oxide (CoS 2 /rGO) binder-free sulfur host is prepared by a bottom-up assembly and hydrothermal treatment. The porous rGO film is stacked by interconnected graphene sheets, and the CoS 2 nanoparticles are dispersed on the graphene sheets uniformly, which effectively obstructs the stacking of graphene sheets. As a binder-free sulfur host, the porous CoS 2 /rGO sulfur host combines the sufficient electron conductivity of the porous rGO framework and the sulfur immobilization interaction of the CoS 2 nanoparticles. This host material demonstrates an initial discharge capacity of 993.5 mAh g −1 and a capacity of 806.7 mAh g −1 after 110 cycles at 0.5 C. Both the capacity and cycling stability of the CoS 2 /rGO cathode were greatly improved over that of rGO. Furthermore, the bottom-up assembly approach provides a novel opportunity for preparing self-supporting graphene-based nanocomposite electrodes. [ABSTRACT FROM AUTHOR]

• A N-doped carbon confined WC/Co 3 W 3 N/Co@NC is prepared via epitaxial growth and calcination. • Porous yolk/shell structure exposes more active sites and boosts the diffusion of the reactants. • Synergistic effect improves the electrocatalytic performance of water splitting. [Display omitted] Designing high-efficiency catalysts with earth-abundance elements for overall water splitting (OWS) in alkaline electrolyte has been unsettled owing to the non-negligible overpotential of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). An electrocatalyst with decent HER and OER activities in the same electrolyte is crucial for sustainable energy storage and conversion device. In this work, a nitrogen-doped porous carbon confined yolk/shell OWS catalyst of WC/Co 3 W 3 N/Co@NC has been prepared via calcination polyhedron encapsulation structure PW 12 @ZIF-8 @ZIF-67 generated by the epitaxial method. Because of the optimized chemical composition, the derived WC/Co 3 W 3 N/Co@NC multisite catalyst has outstanding OWS performance in 1 M KOH solution. For example, to reach a current density of 10 mA cm-2, it only needs low overpotentials of 141 and 280 mV for the HER and OER, respectively. By using the easy operation and classical bubble extraction method, we find that the Faraday efficiencies of the catalyst for HER and OER are 94.3% and 97.4%, respectively. Moreover, taking advantage of the micropores and mesopores in the yolk/shell structure, it exhibits enhanced stability and promoted diffusion kinetics. This work initiates an effortless approach to the synthesis of the highly efficient yolk/shell carbon-based OWS electrocatalyst. [ABSTRACT FROM AUTHOR]

Electrolysis of seawater is a promising approach to address freshwater scarcity and indirectly mitigate the energy crisis. In this context, the oxygen evolution reaction (OER) plays a crucial role as one of the half−reactions in water electrolysis. However, the development of cost−effective non−precious metal catalysts for OER remains a challenging issue. In this study, we present a facile method for synthesizing Prussian blue sulfides supported on nickel foam (NF) at ambient temperature. The resulting S−FeNi@NF catalyst demonstrates remarkable electrocatalytic performance with an overpotential of only 330 mV at a current density of 100 mA cm⁻² in simulated seawater. Notably, the catalyst exhibits excellent corrosion resistance and electrochemical stability, maintaining its effectiveness for over 120 h following vulcanization. Furthermore, we assessed the catalysts for their resistance to chloride ion corrosion in natural seawater and observed no significant signs of etching for more than 30 days. This outstanding stability of the S−FeNi@NF material can be attributed to its dual protective mechanisms against chloride ions, which encompass both corrosion resistance and the repulsion of chloride ions during electrochemical processes. Our findings offer a fresh perspective on catalyst design, particularly in the context of shielding against chloride−induced degradation in direct seawater electrolysis. • The negatively charged surface of the vulcanised catalyst effectively resists chloride etching. • No visible structural damage after 30 days of immersion in natural seawater. • In situ growth of PBA materials on NF effectively enhances conductivity and facilitates the four-electron transfer process. • The self-supporting electrocatalysts derived from PBA exhibit dual resistance to the effects of chloride ions. [ABSTRACT FROM AUTHOR]

• A high-performance ORR/OER catalyst is prepared by using corn stalks as precursor. • FeN x and FeC x originated from Fe, N-dual doped improve catalytic performance. • The Fe-MNC catalyst achieves an excellent performance for Zn-air batteries. [Display omitted] The development of affordable and perdurable electrocatalysts for oxygen reduction/evolution reaction (ORR/OER) has been considered as an alternative to address the global energy crisis and grievous environmental pollution. Therefore, exhaustively developing low-cost bifunctional electrocatalysts is of significance especially derived from the ubiquitous carbonous biomass materials. Here, an advanced catalyst of Fe, N-dual doped mesoporous and microporous carbon nanosheets (Fe-MNC) is synthesized by using Fe-pyridine coordination complex as the sources of Fe, N and corn stalk soot as the support. The Fe-MNC possesses vigorous electrocatalytic performance for ORR with an E 1/2 of 0.85 V. Moreover, for OER, the overpotential is as low as 309 mV at the current density (j) of 10 mA cm−2 and the Tafel slope is 127 mV dec−1. What's more, a rechargeable Zn-Air battery is constructed based on Fe-MNC as the air cathode. This work not only establishes an easy access and sustainable way to produce a cost-cutting and highly efficient ORR/OER catalyst, but also paves a new way for a greater value-added utilization of biomass carbon for sustainable energy conversation. [ABSTRACT FROM AUTHOR]