Enhanced Thermal- and Photostability of Trace Pyrazine-Incorporated Hydrogen Boride Nanosheets

Hydrogen boride (HB) nanosheets are emerging hydrogen-rich materials with controllable hydrogen-release properties under UV, electrochemical, and thermal stimuli. However, their practical application in high-temperature environments and harsh conditions, such as neutron shielding, requires improved stability against heat and light exposure. Herein, the synthesis of pyrazine-incorporated HB nanosheets (Pyrazine-HB) is reported via a simple solution-mixing and drying process. Despite a low pyrazine content of ≈2.9 mol%, Pyrazine-HB exhibits significantly enhanced thermal stability, with a hydrogen release temperature ≈200 K higher than that of pure HB. Moreover, its hydrogen release under UV and visible light irradiation is markedly suppressed. Brunauer-Emmett-Teller analysis reveals an increased surface area upon pyrazine incorporation, suggesting intercalation between HB layers. This is further supported by transmission electron microscopy, which showed changes in interlayer spacing indicative of molecular intercalation. The improved stability of Pyrazine-HB is attributed to expanded interlayer spacing, which prevents interlayer hydrogen recombination. This study presents a facile and effective molecular-level strategy for tuning the thermal stability and photostability of HB nanosheets, thereby advancing their potential for energy-related applications.