A convenient and walkable protocol has been established to simplify the fabrication of surface-engineered heterojunctions between 2D/2D g-C3N4-β-SnWO4. The method involves a one-step, simultaneous thermal exfoliation-deposition technique that utilizes bulk carbon nitride and stannous tungstate in a thermal spreading process. The prepared catalysts demonstrate excellent performance in the photocatalytic decomposition of Clioquinol (a neurotoxic drug) and dopamine sensing. The results indicate that the optimal loading of carbon nitride is 12 %, with this catalyst completely decomposing clioquinol within 80 min. Lower and higher loadings result in inferior performance due to ineffective interfacial contact, the formation of a bulk-like carbon nitride phase, and the encapsulation of stannous tungstate particles, respectively. A plausible mechanism has been proposed based on scavenger studies. The 12 % g-C3N4-SnWO4 sample exhibits the lowest charge transfer resistance and demonstrates good dopamine sensing properties. The selective sensing performance has been confirmed in the presence of glucose, ascorbic acid, and urea. The limit of detection (LOD) for the 12 % g-C3N4-SnWO4 sensor system is determined to be 1.78 μM.