Heteroatom doping of graphene effectively modifies surface charge, defect density, and electronic structure, with multi-heteroatom co-doping enhancing bond polarization, charge redistribution, and electrochemical performance for advanced energy storage, conversion, and other technological applications. In this work, we report a one-step synthesis of di- and tri-doped graphene via the simultaneous incorporation of fluorine and boron into pristine as well as S- and N-doped graphene, starting from commercially available N- or S-doped graphene. Mild gas–solid fluorination was performed using elemental fluorine diluted in an inert nitrogen atmosphere at controlled temperatures. The presence of a boron-containing precursor enables the in situ generation of BF3, which acts as an effective boron-doping agent during the fluorination process. This approach allows, for the first time, the controlled synthesis of F/B/S-, and F/B/N- -tri-doped graphene materials through a single-step reaction. The doping mechanisms and structural evolution were elucidated using complementary characterization techniques, including Fourier-transform infrared (FTIR) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy (19F, 11B and 13C), thermogravimetric analysis (TGA) coupled with mass spectrometry (MS) and infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and (scanning)transmission electron microscopy ((S)TEM). The results demonstrate that hexagonal boron nitride and molecular fluorine act as precursors for the in situ generation of BF3, which, together with F2, enables efficient and homogeneous incorporation of fluorine and boron into heteroatom-doped graphene carbon frameworks.

Copper Antimony Tin Sulphide (CATS, CuSbSnS₃) was produced through both hydrothermal and solid-state synthesis routes, employing various sulfur precursors. X-ray diffraction (XRD) analysis verified the development of a polycrystalline CuSbSnS₃ phase, with thiourea (TU) synthesis delivering the most well-defined crystal structures. Field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) analyses revealed nanocrystalline morphologies, with flake-like particles of ~ 60 nm and uniformly agglomerated nanoparticles ranging from 5 to 10 nm, indicating distinct size distributions. Optical studies showed a suitable band gap range (1.25–1.70 eV), with enhanced light absorption in the 480–1000 nm region. Post-annealing treatments improved the electrical conductivity, as a result of reduced resistivity, and inhibited grain growth. Photo-electrochemical analysis under light irradiation indicated that TU-sourced CATS exhibited superior charge transport behavior, achieving the lowest charge transfer resistance (50 Ω), highest conductivity (9.41 × 10⁶ Ω⁻¹·cm⁻¹), carrier mobility (2.50 × 10⁵ cm²·V⁻¹·s⁻¹), and bulk carrier concentration (2.35 × 10²⁰ cm⁻³). As a result, the TU-derived CATS achieved the highest power conversion efficiency of 7.77%, highlighting its strong promise for photoelectric and solar energy applications.