Heavy metal poisoning has a life-threatening impact on the human body to aquatic ecosystems. This necessitates designing a convenient green methodology for the fabrication of an electrochemical sensor that can detect heavy metal ions efficiently. In this study, boron (B) and nitrogen (N) co-doped laser-induced porous graphene (LIG_BN) nanostructured electrodes were fabricated using a direct laser writing technique. The fabricated electrodes were utilised for the individual and simultaneous electrochemical detection of lead (Pb²⁺) and cadmium (Cd²⁺) ions using a square wave voltammetry technique (SWV). The synergistic effect of B and N co-doping results in an improved sensing performance of the electrode with better sensitivity of 0.725 µA/µM for Pb²⁺ and 0.661 µA/µM for Cd²⁺ ions, respectively. Moreover, the sensing electrode shows a low limit of detection of 0.21 µM and 0.25 µM for Pb²⁺ and Cd²⁺ ions, with wide linear ranges from 8.0 to 80 µM for Pb²⁺ and Cd²⁺ ions and high linearity of R² = 0.99 in case of simultaneous detection. This rapid and facile method of fabricating heteroatom-doped porous graphene opens a new avenue in electrochemical sensing studies to detect various hazardous metal ions.

Nanostructured boron-doped diamond (BDD) offers a sizeable ion-accessible area, high mechanical robustness, and high electrical conductivity, and could be a suitable electrode for high-performance electrochemical (EC) supercapacitors. Herein, two morphological BDD films, namely, boron-doped microcrystalline diamond (BMCD) and boron-doped ultra-nanocrystalline diamond (BUNCD), are employed for nanostructuring. The diamond nanopillars are fabricated via the Au mask-assisted reactive ion etching (RIE) method. The nanostructured samples of BMCD and BUNCD are termed BMCD_N and BUNCD_N. The Raman spectroscopy and X-ray photoelectron spectroscopy measurements of these nanostructured samples confirm the presence of sp² in sp³-bonded carbon, which combine to offer good EC activity of sp² and exceptional stability of sp³ carbon. These nanostructured BDD samples with enhanced surface area are utilized as electrode materials to construct an electric double-layer capacitor and pseudocapacitor. In 1 M Na₂SO₄ solution, the maximum specific capacitance of BMCD_N is found to be 0.0852 mF cm⁻², whereas, for BUNCD_N the value is 0.0784 mF cm⁻². The electrochemical analysis of these samples shows they exhibit superior electron transfer kinetics with 80% capacitance retention after 2000 cycles, which indicates the suitable utilization of these nanostructured samples as electrodes in EC supercapacitors.

The miniaturization of electrochemical supercapacitors (EC‐SCs) requires electrode materials that are both durable and efficient. Boron‐doped diamond (BDD) films are an ideal choice for EC‐SC due to their durability and exceptional electrochemical performance. In this study, nanostructured boron‐doped ultra‐nanocrystalline diamonds (NBUNCD) are fabricated on Si micro‐pyramids (Si _P ) using a simple reactive ion etching (RIE) process. During the etching process, the high aspect ratio and the induction of sp ² graphite in these nanorod electrodes achieved a maximum specific capacitance of 53.7 mF cm ⁻² at a current density of 2.54 mA cm ⁻² , with a 95.5% retention after 5000 cycles. Additionally, the energy density reached 54.06 µW h cm ⁻² at a power density of 0.25 µW cm ⁻² . A symmetric pouch cell using NBUNCD/Si _P exhibited a specific capacitance of 0.23 mF cm ⁻² at 20 µA cm ⁻² , an energy density of 31.98 µW h cm ⁻² , and a power density of 0.91 µW cm ⁻² . These superior EC properties highlight NBUNCD/Si _P ’s potential for advancing miniaturized supercapacitors with high capacitance retention, cycle stability, and energy density.