Developing cost‐effective and high‐efficiency electrocatalysts toward alkaline oxygen evolution reaction (OER) is crucial for water splitting. Amorphous bimetallic NiFe‐based (oxy)hydroxides have excellent OER activity under alkaline media, but their poorly electrical conductivity impedes the further improvement of their catalytic performance. Herein, a bimetallic NiFe‐based heterostructure electrocatalyst that is composed of amorphous NiFe(OH)x and crystalline pyrite (Ni, Fe)Se2 nanosheet arrays is designed and constructed. The catalyst exhibits an outstanding OER performance, only requiring low overpotentials of 180, 220, and 230 mV at the current density of 10, 100, and 300 mA cm−2 and a low Tafel slope of 42 mV dec−1 in 1 m KOH, which is among the state‐of‐the‐art OER catalysts. Based on the experimental and theoretical results, the electronic coupling at the interface that leads to the increased electrical conductivity and the optimized adsorption free energies of the oxygen‐contained intermediates plays a crucial role in enhancing the OER activities. This work focusing on improving the OER performance via engineering amorphous‐crystalline bimetallic heterostructure may provide some inspiration for reasonably designing advanced electrocatalysts.

Development of low-cost, high performance and stable non-noble electrocatalysts with both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities for overall water splitting is essential for future energy supply. Herein, for the first time, a facile and ultrafast synthetic method has been reported to fabricate nickel sulfide (Ni3S2) films on Ni foam (Ni3S2/NF) as efficient bifunctional electrodes for overall water splitting through direct dropping of mercaptoethanol solution followed by annealing at 300 °C for only 50 s. Thanks to the integrated three-dimensional (3D) configuration, the obtained Ni3S2/Ni foam exhibits excellent activity and stability for HER and OER with low overpotentials of 131 and 312 mV, respectively, to attain a current density of 10 mA cm-2 in alkaline media. Ni(OH)x species formed on the Ni3S2 surface serves as the actual catalytic site during OER reaction. Given the well-defined bifunctionality, an overall water-splitting device using two identical Ni3S2/NF electrodes delivers a current density of 10 mA cm-2 at a low cell voltage of 1.68 V in an alkaline water electrolyzer. This approach is promising as a simple method for depositing a wide range of useful transition metal sulfide electrocatalysts on corresponding metal substrate bifunctional electrodes for overall water splitting, shedding some light on the development of functional materials in energy chemistry.

The development of low-cost, high-activity, durable non-precious metal bifunctional electrocatalysts is of great significance for the producing hydrogen by water electrolysis. In this work, we have prepared a new Al-doped...

Antimony selenide (Sb 2 Se 3 ) semiconductor with a narrow band gap is regarded as an ideal candidate for the next-generation broadband photodetectors. However, the photodetectors based on the binary Sb 2 Se 3 semiconductor suffer from low responsivity (R λ ) and external quantum efficiency due to the intrinsic low electrical conductivity. To address the issue, we introduce a low-valence Ni cation (Ni 2+ ) into the binary Sb 2 Se 3 ((Sb 1−x Ni x ) 2 Se 3 ) nanorods synthesized by a facile hot-injection process. With increasing Ni-doping concentration, the (Sb 1−x Ni x ) 2 Se 3 nanorods exhibit a significant increase of electrical conductivity from 4.983 × 10 −5 to 4.011 × 10 −4 Ω −1 m −1 . The photodetector based on (Sb 0.995 Ni 0.005 ) 2 Se 3 nanorod film exhibits an excellent responsivity of 18.9 mA/W under white light illumination of 45 mW/cm 2 at an applied bias voltage of 3 V, which is an approximately 19fold higher than that of the pristine Sb 2 Se 3 nanorod photodetector. Moreover, the density functional theory calculation has demonstrated that the Ni 2+ doped into Sb 2 Se 3 will preferentially occupy the Sb site and introduce a shallow energy level of acceptor, resulting in the enhancement of electrical conductivity, which is consistent with the experimental result. Therefore, the work proves the substitution of Sb site with a low-valence metal cation into Sb 2 Se 3 is an effective strategy to improve the performance of the Sb 2 Se 3 -based photodetector.

Designing dual-metal atoms efficient bifunctional oxygen electrocatalyst by a one-step adsorption and a pyrolysis steps.