Assess the learner's ability to design a reproducible laboratory experiment and complementary computational model to develop and characterize a novel visible‑light photocatalyst for efficient CO2→CH4 conversion. Scope includes proposing a clear synthesis and scale-up‑ready protocol with controls and replication strategy; selecting and justifying characterization techniques (e.g., UV‑Vis, XRD, XPS, TEM, BET); designing a photocatalytic reactor and light source, gas sampling and GC quantification, and metrics (quantum efficiency, selectivity, TON/TOF); outlining DFT/periodic modeling of band structure, adsorption energies, and reaction pathways; linking computational predictions to experimental validation, data analysis, uncertainty estimation, and safety/environmental considerations.