In Situ Deciphering Internal Electric Field-Accelerated Charge Dynamics and Stable Methanol Dehydrogenation with a 2 <i>D</i> /1 <i>D</i> ZnIn ₂ S ₄ /CdS Heterojunction

Refining interfacial charge migration routes is vital for boosting the dehydrogenation performance of liquid organic hydrogen carriers (LOHCs). Herein, the ZnIn 2 S 4 /CdS heterostructure was effectively fabricated via a dual-step solvothermal approach. Integrating ultraviolet photoelectron spectroscopy (UPS) with density functional theory (DFT) computations, we verified the formation of an internal electric field (IEF) pointing from ZnIn 2 S 4 to CdS, driven by their distinct work functions. Time-resolved photoluminescence (TR–PL) measurements demonstrated that the photoinduced carrier lifetime for the 0.6ZIS/CS composite was notably extended to 2.36 ns. This delayed decay behavior signifies an improved charge transport route promoted by the IEF, thereby favoring the adsorption and transformation of reactive intermediates. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirmed the swift activation of methoxy species (*CH 3 O) alongside the production of formaldehyde (*CH 2 O) over the 0.6ZIS/CS surface. Aided by these refined intermediate and photoexcited carrier migration channels, the light-driven methanol dehydrogenation process is effectively propelled. The 0.6ZIS/CS sample achieves a H 2 evolution of 0.88 mmol g –1 ·h –1 within the methanol mixture, with 1 H NMR identifying valuable formaldehyde as the primary oxidized product. Ultimately, this research clarifies and introduces an IEF-regulated mechanism governing the surface reaction kinetics during photocatalytic dehydrogenation.