Developing high-performance electrode materials is in high demand for the development of supercapacitors. Herein, defect and interface engineering has been simultaneously realized in NiMoO4 nanowire arrays (NWAs) using a simple sucrose coating followed by an annealing process. The resultant hierarchical oxygen-deficient NiMoO4@C NWAs (denoted as “NiMoO4−x@C”) are grown directly on conductive ferronickel foam substrates. This composite affords direct electrical contact with the substrates and directional electron transport, as well as short ionic diffusion pathways. Furthermore, the coating of the amorphous carbon shell and the introduction of oxygen vacancies effectively enhance the electrical conductivity of NiMoO4. In addition, the coated carbon layer improves the structural stability of the NiMoO4 in the whole charging and discharging process, significantly enhancing the cycling stability of the electrode. Consequently, the NiMoO4−x@C electrode delivers a high areal capacitance of 2.24 F cm−2 (1720 F g−1) at a current density of 1 mA cm−2 and superior cycling stability of 84.5% retention after 6000 cycles at 20 mA cm−2. Furthermore, an asymmetric super-capacitor device (ASC) has been constructed with NiMoO4−x@C as the positive electrode and activated carbon (AC) as the negative electrode. The as-assembled ASC device shows excellent electrochemical performance with a high energy density of 51.6 W h kg−1 at a power density of 203.95 W kg−1. Moreover, the NiMoO4//AC ASC device manifests remarkable cyclability with 84.5% of capacitance retention over 6000 cycles. The results demonstrate that the NiMoO4−x@C composite is a promising material for electrochemical energy storage. This work can give new insights on the design and development of novel functional electrode materials via defect and interface engineering through simple yet effective chemical routes.

Charging electrochemical devices by light irradiation may bring an essential change in energy-storage technologies. Herein, nickel copper mixed oxides (NiCuOx) based bifunctional photoelectrodes for integrated energy conversion and energy storage...

The use of broadband light energy is important for enhancing photoenergy conversion. However, bifunctional materials that can efficiently harvest solar energy to assist electrochemical energy storage are difficult to prepare. Herein, copper foam (CF)-supported cuprous sulfide (Cu 2 S) heteroarrays (CS HAs) with enriched sulfur (S) vacancies (V S ) were designed for photo-rechargeable pseudocapacitors. A direct hydrothermal sulfurization of CF first resulted in the growth of CS HAs with leaf-like heterostructures. Subsequent partial oxidation of S 2− in FeCl 3 aqueous solution enriched the V S within the leaf-like structures. In addition, CuCl and Cu 2 O were formed from Cu 2 S during FeCl 3 treatment to derive a bifunctional photoelectrode with ternary components, thus further broadening the light absorption region. Thus, the optimal CS HAs have demonstrated areal capacitances of 1440-1048 mF cm −2 with the assistance of the photoelectric/ thermal effects of light energy, delivering remarkable photoenhancements of 25%-35%. The asymmetrical pseudocapacitors fabricated from the optimal photoelectrodes delivered a high areal capacitance of 670 mF cm −2 after 6000 cycles, suggesting a promising application in transparent light-driven energy devices.

Lithium−sulfur batteries (LSBs) hold a great potential as the next-generation electrochemical energy storage and conversion system owing to their high theoretical specific capacity (1675 mAh g-1). However, the shuttling of...