As an important neurotransmitter, the concentration of dopamine (DA) reflects certain physiological conditions and DA-related diseases. Rapid monitoring of DA levels is of great significance in regulating body health. However, regular electrochemical DA sensors suffer from poor sensitivity, low selectivity and interference immunity, as well as a complex preparation process. Herein, we developed an accessible and cost-effective electrochemical sensor with a copper indium selenide (CuInSe₂ or CIS)-modified screen-printed carbon electrode for DA discrimination. This DA sensor was developed using a facile one-step hydrothermal method without high-temperature quenching. Benefitting from the inherent merits of CIS and the conversion of Cu²⁺ and Cu⁺ during the catalytic reaction, the sensor attained both excellent sensitivity (2.511 μA·µM⁻¹·cm⁻¹) and selectivity among multiple substances interfering with DA. This work demonstrates the potential to improve the analytical performance of traditional electrochemical sensors.

Developing novel supercapacitor electrodes with high energy density and good cycle stability has aroused great interest. Herein, the vertically aligned CoNiO2/Co3O4 nanosheet arrays anchored on boron doped diamond (BDD) films are designed and fabricated by a simple one-step electrodeposition method. The CoNiO2/Co3O4/BDD electrode possesses a large specific capacitance (214 mF cm−2) and a long-term capacitance retention (85.9% after 10,000 cycles), which is attributed to the unique two-dimensional nanosheet architecture, high conductivity of CoNiO2/Co3O4 and the wide potential window of diamond. Nanosheet materials with an ultrathin thickness can decrease the diffusion length of ions, increase the contact area with electrolyte, as well as improve active material utilization, which leads to an enhanced electrochemical performance. Additionally, CoNiO2/Co3O4/BDD is fabricated as the positive electrode with activated carbon as the negative electrode, this assembled asymmetric supercapacitor exhibits an energy density of 7.5 W h kg−1 at a power density of 330.5 W kg−1 and capacity retention rate of 97.4% after 10,000 cycles in 6 M KOH. This work would provide insights into the design of advanced electrode materials for high-performance supercapacitors.

A reasonable design of nickel-based catalysts is key to efficient and sustainable energy conversion. For electrocatalytic materials in alkaline electrolytes, however, atomic-level control of the active sites is essential. Moreover, the well-defined surface structure contributes to a deeper understanding of the catalytic mechanism. Here, we report the loading of defective nickel–cobalt layered double hydroxide nanosheets (Ni₂Co-LDH@C) after carbonization of silk. Under the precise regulation of the local coordination environment of the catalytic active site and the presence of defects, Ni₂Co-LDH@C can provide an ultra-low overpotential of 164.8 mV for hydrogen evolution reactions (HERs) at 10 mA cm⁻², exceeding that of commercial Pt/C catalysts. Density functional theory calculations show that Ni₂Co-LDH@C optimizes the adsorption energy of the intermediate and promotes the O-O coupling of the active site in the oxygen evolution reaction. When using Ni₂Co-LDH@Cs as cathodes and anodes to achieve overall water splitting, a low voltage of 1.63 V is required to achieve a current density of 10 mA cm⁻². As an ideal model, Ni₂Co-LDH@C has excellent water splitting properties and has the potential to develop water–alkali electrocatalysts.

In this work, we report the design and synthesis of non-noble metal-based electrocatalysts for effective overall water splitting in alkaline solutions for the development of hydrogen energy. The electrocatalysts were synthesized by a one-step hydrothermal method similar to microflower structure electrocatalysts. The synergistic effect between the special Echinops sphaerocephalus nanostructure and the nanowire can greatly improve the conductivity of the nanomaterial due to its high activity quality, fast ion transport, and exposure of more active sites, thus resulting in a better catalytic activity and a longer material stability of the electrocatalyst. For Mn_xCo_yO₄/Ti in alkaline aqueous solutions, a current density of 10 mA cm⁻² is required when the voltage is only 1.60 V. In addition, the hydrogen evolution activity of electrocatalysts is 168 mV at 10 mA cm⁻², the Tafel slope is 174 mV dec⁻¹, and the oxygen evolution activity of electrocatalysts is 229 mV at 10 mA cm⁻², which showed good long-term stability within 12 h, even better than that of previously reported electrocatalysts.