High-purity sodium metaborate synthesis via controlled thermal decomposition of sodium borohydride: Characterization for sustainable applications

A catalyst-free synthesis of high-purity sodium metaborate (NaBO₂) is reported, which is carried out using a controlled thermal decomposition of 2 g (99.99% pure) sodium borohydride (NaBH₄) in an alumina crucible. The process reduces the risk of auto-ignition of hydrogen and allows the possibility of hydrogen capture. X-ray photoelectron spectroscopy (XPS) verifies tetrahedral borate coordination (B 1s at ∼190.2 eV) and ionic sodium (Na 1s at ∼1071.9 eV), while X-ray diffraction (XRD) shows a highly crystalline structure with a dominating (111) peak at 2θ = 31.82°, confirming a dense Na-B plane. The stacked crystallites that resemble petals are observable under scanning electron microscopy (SEM), enhancing the reactivity and solubility. As-synthesized NaBO 2 can be used in hydrogen storage, catalysis, glass, and agriculture. Its optimized conditions and detailed characterization make it possible to sustain chemical cycles and high performance. The catalyst-free, capped-crucible method has higher purity, safety, and hydrogen-capture efficiency than traditional catalyzed or open-system processes, proceeding towards sustainable production of NaBO₂ and closed-loop hydrogen storage.