Photo-reforming methanol into valuable chemicals represents an energetically sustainable alternative to conventional thermal catalysis, yet controlling-specific C–C coupling way still remains elusive. In this work, we report a sulfide-based photocatalytic paradigm, where atomic-level control of nickel species directly dictates reaction selectivity. The electrostatic constructing ZnIn₂S₄/Zn_0.5Cd_0.5S (ZIS/ZCS) heterostructures enable single atom Ni to facilitate ethylene glycol (EG) production with a rate of 11.2 mmol·g_cat⁻¹·h⁻¹, surpassing reported non-precious metal systems, whereas the Ni aggregates drive exclusive formaldehyde formation. The operando spectroscopy and density functional theory reveal dual roles of Ni as electron reservoir and chemical bond breakage inducers, lowering C–H activation barriers while stabilizing ·CH₂OH intermediates for cross-coupling. This interfacial configuration engineering creates an electron highway that couples carrier dissociation with radical recombination kinetics, achieving atom-economic steering of methanol oxidative valorization. The metal dispersion assisting catalysis correlation here provides a design blueprint for selective bond scission and reconstruction in sustainable organic synthesis.