Zhibin Liu

A superhydrophilic “nanoglue” for stabilizing metal hydroxides onto carbon materials for high-energy and ultralong-life asymmetric supercapacitors

Coupling electroactive species with carbon supports to fabricate hybrid electrodes holds promise for high-performance supercapacitors. Nevertheless, the poor compatibility and weak bonding between carbon substrates and electroactive species remain a bottleneck to be tackled. Herein, we present a superhydrophilic “nanoglue” strategy for stabilizing NiCo-layered double hydroxide (NiCo-LDH) nanosheets on inert carbon cloth (CC) by employing a nitrogen-doped (N-doped) carbon layer as the structure/interface coupling bridge to make hybrids (denoted as CC–NC-LDH) for supercapacitors. Such a “nanoglue” on a CC substrate results in the formation of a superhydrophilic surface/interface, which is favorable for the robust and uniform growth of NiCo-LDH on the CC, and helps effectively tune the electronic structural states and results in a strong coupling interaction between the CC and NiCo-LDH nanosheets. Benefiting from these integrated merits, asymmetric supercapacitors fabricated with the CC–NC-LDH hybrids as the positive electrode and typical activated carbon as the negative electrode deliver a high energy density of 69.7 W h kg−1 at a power density of 0.8 kW kg−1, with an ultra-low average capacitance fade rate of ∼0.00065% per cycle within 20 000 cycles at a current density of 10 A g−1. This superhydrophilic “nanoglue” strategy can also be extended to assemble other kinds of active species on different inert substrates, and holds the potential for creating efficient and robust electrode materials for energy-related devices.

Ultrasmall diiron phosphide nanodots anchored on graphene sheets with enhanced electrocatalytic activity for hydrogen production via high-efficiency water splitting

Transition metal phosphides (TMP) have been one of the excellent candidates as low-cost and high-efficiency catalysts for the sustainable hydrogen evolution reaction (HER). Nevertheless, construction of TMP with abundant exposed active sites is of urgent concern and highly desirable for the HER. Herein, we report a novel strategy to configure integrated active site-enriched architectures (Fe2P-ND/FG) composed of diiron phosphide (Fe2P) nanodots with a diameter of ∼2.5 nm uniformly anchored on porous and fluffy graphene sheets (FG). The interconnected conductive networks within porous FG favor the formation of uniformly and highly dispersed Fe2P nanodots, finally helping the promotion of fast electrolyte ion and electron transfer during the electrochemical process. Compared with bulk Fe2P, these ultrasmall Fe2P nanodots lead to abundant exposed edges and atoms. Benefiting from the highly exposed active sites derived from Fe2P nanodots and superior electrical conductivity stemming from an interconnected graphene matrix, the as-made Fe2P-ND/FG hybrids exhibit outstanding HER catalytic activity and stability. Overpotentials as low as 44 and 91 mV are required to achieve current densities of 2 and 10 mA cm−2, respectively. The present strategy provides a novel approach for configuring electrode materials with highly exposed active sites for high-efficiency energy storage/conversion devices.

High‐Stacking‐Density, Superior‐Roughness LDH Bridged with Vertically Aligned Graphene for High‐Performance Asymmetric Supercapacitors

The high-performance electrode materials with tuned surface and interface structure and functionalities are highly demanded for advanced supercapacitors. A novel strategy is presented to conFigure high-stacking-density, superior-roughness nickel manganese layered double hydroxide (LDH) bridged by vertically aligned graphene (VG) with nickel foam (NF) as the conductive collector, yielding the LDH-NF@VG hybrids for asymmetric supercapacitors. The VG nanosheets provide numerous electron transfer channels for quick redox reactions, and well-developed open structure for fast mass transport. Moreover, the high-stacking-density LDH grown and assembled on VG nanosheets result in a superior hydrophilicity derived from the tuned nano/microstructures, especially microroughness. Such a high stacking density with abundant active sites and superior wettability can be easily accessed by aqueous electrolytes. Benefitting from the above features, the LDH-NF@VG can deliver a high capacitance of 2920 F g-1 at a current density of 2 A g-1 , and the asymmetric supercapacitor with the LDH-NF@VG as positive electrode and activated carbon as negative electrode can deliver a high energy density of 56.8 Wh kg-1 at a power density of 260 W kg-1 , with a high specific capacitance retention rate of 87% even after 10 000 cycles.