In situ Raman insights into amino acid-mineral synergy during methane hydrate nucleation and structural evolution

Synergistic interactions between organic molecules and mineral particles at sedimentary interfaces play a key role in methane hydrate formation, yet the mechanisms of amino acid–mineral regulation remain unclear. Here, in situ confocal Raman microscopy with a high-pressure fused-silica capillary cell was used to monitor methane dissolution, nucleation, and early growth at the micron scale under controlled conditions. L-glutamic acid (Glu) substantially shortened induction time ( ≈ 0.97 min) and induced a small-cage-preferred hydrate structure ( ≈ 0.955; ≈ 5.96), yielding the highest volumetric gas storage capacity ( ≈ 166.83 m 3 CH 4 per m 3 hydrate) and energy density ( ≈ 985.93 MJ per m 3 hydrate). In contrast, L-leucine (Leu) showed a selective, condition-dependent promotion of nucleation: when combined with 1.0% SiO 2 , it increased nucleation temperature (261.15 K) and shortened induction time ( ≈ 1.87 min), while yielding little improvement in structural compactness or gas-storage performance. Collectively, interfacial chemical properties, rather than surface areas, dominated hydrate nucleation efficiency and the early structural signatures of hydrate formation, as reflected by Raman-derived cage occupancy and hydration number. These findings provided new lines of experimental evidence supporting potential mechanisms of amino acid–mineral interfacial regulation and offered a practical perspective for interface-engineered strategies in hydrate-based gas storage and stability control.