Electrochemical performance of BN – Me (Ti, Cr, Al, Zr) composite nanopowders synthesized under concentrated light with reduced surface-driven contributions

BN–Ti, BN–Cr, BN–Al, and BN–Zr composite nanopowders were synthesized under concentrated light in nitrogen and tested as cathodically polarized electrodes in 0.1 M H₂SO₄. The ultrafast heating route produced structurally heterogeneous, partially oxidized composites, which were heat-treated at 400 °C to reduce surface-defect effects. XRD and Raman revealed amorphous/turbostratic BN domains with boron oxides (B₂O₃, H₃BO₃) and dispersed metal oxides (TiO₂, ZrO₂, Cr₂O₃, γ-Al₂O₃), without bulk nitride/boride phases. TEM showed additive-dependent architectures: BN–Cr formed fibrous networks of high surface area, while BN–Ti/Zr produced agglomerated nanoparticles. Electrochemically, BN–Cr delivered the highest instantaneous currents and earliest polarization onset, BN–Al the largest integrated charge via acid-induced restructuring of γ-Al₂O₃, and BN–Ti/Zr intermediate capacitive responses. Cycling confirmed BN’s stabilizing role, suppressing oxide dissolution and enabling beneficial surface reconstruction. These results establish BN–metal composites as durable, composition-tunable electrodes in acidic environments, with additive choice governing architecture, kinetics, and charge-storage behavior.