Distinct Solvent Effects on Dispersibility and Photoinduced Hydrogen Release of Hydrogen Boride Sheets.

2D materials are highly sensitive to their surrounding chemical environment, making solvent selection important for both processing and functional performance. Hydrogen boride (HB) sheets are hydrogen-containing 2D materials with promising liquid-phase and hydrogen-related functionality. However, the role of HB-solvent interactions remains poorly understood because only a limited solvent range has been explored. Here, HB sheet dispersibility and photoinduced hydrogen release are systematically investigated in solvents with different characteristics. Visual observation, gravimetric analysis, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and dynamic light scattering show that HB sheets disperse most effectively in selected polar aprotic solvents, particularly N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF), whereas nonpolar solvents are ineffective and ultrapure water (UPW) shows only partial dispersion. Dispersibility is related to solvent polarity and donor number, while Hansen solubility parameter (HSP) analysis indicates that compatibility reflects a balance of dispersive (δD), polar (δP), and hydrogen-bonding (δH) interactions. In contrast, photoinduced hydrogen release is highest in UPW and alcohols and correlates most clearly with the hydrogen-bonding component rather than with dispersibility. These results indicate that dispersibility and hydrogen release arise from different aspects of HB-solvent interactions, providing practical guidelines for HB processing and photochemical applications.