摘要
We report a low-temperature chemical vapor deposition approach that enables the direct formation of GaS at 300 degrees C and controlled transformation to Ga2S3 by tuning the sulfurization temperature and time. Comprehensive structural analyses reveal that pure GaS forms below 450 degrees C, while mixed GaS/Ga2S3 heterostructures emerge above 500 degrees C and evolve to phase-pure alpha '-Ga2S3 after prolonged annealing at 700 degrees C. X-ray photoelectron spectroscopy (XPS) confirms a time-dependent decrease in the GaS:Ga2S3 ratio from 1:1.56 to complete Ga2S3 conversion, accompanied by binding energy shifts that evidence interfacial electron transfer from GaS to Ga2S3. Transmission electron microscopy further resolves atomically sharp GaS/Ga2S3 interfaces with coherent lattice matching. Electrochemical impedance spectroscopy demonstrates that M-Ga2S3/GaS heterostructures, containing an intermediate Ga2S3 fraction, exhibit the lowest charge-transfer resistance (similar to 37 k Omega) and the highest steady-state photocurrent (similar to 400 nA). The heterostructures deliver an exceptional hydrogen evolution rate of 2.93 mmol g(-1) h(-1), a 3.3-fold increase over that of pure Ga2S3. This outstanding activity is attributed to a type-II band alignment that drives electrons from GaS to Ga2S3 and holes in the opposite direction, enhancing charge separation and suppressing recombination. Our results highlight a scalable low-temperature route to gallium sulfide heterostructures with precisely tunable phase composition and superior photocatalytic hydrogen production performance.