An approach to exploring and developing synthetic pathways based on colloidal and plasma deposition processes combined with rapid photonic heating of high entropy oxide (HEO) materials will be presented – to break present limitations and bottlenecks in achieving stable and efficient photo- and electrochemical Fuel Synthesis. HEOs are a new class of single-phase materials comprising near-equimolar compositions of 5 metal cations or more with remarkable thermodynamic and chemical stability, enhanced properties, and tunable multifunctionalities that can present material properties between the constituent metal-oxides, and entirely new properties. Therefore, interest in HEOs is growing exponentially as materials for energy conversion. However, as photo- and electrocatalytic materials, HEOs are still underdeveloped for two significant interrelated challenges: i) material complexity, which often exceeds the robustness of their in-depth characterization and research and development, and ii) synthetic issues of these ceramic compounds, which involve energy-intensive fabrication processes, potentially limiting control of structural and electronic quality and tunable multifunctionalities. Furthermore, electronic quality is critical in the case of light-absorbing semiconductors for solar-energy conversion (note: when typical conventional heating methods are used, using glass-based transparent conductive substrates is limited due to the substrates’ thermal stability). In light of these challenges, there is a pressing need for innovative approaches to close synthesis gaps and identify pathways for achieving high-quality multi-functional HEOs to advance their research and development. In my talk, I will demonstrate the practicality of our approach using the rare earth HEO materials and the model HEO (MgZnCuCoNi)O for photoelectrochemical and electrochemical conversion (respectively), showing to enhance their properties either as free-standing powder form or thin film (photo)electrodes. In summary, our synthesis methods can successfully address a primary need to focus on novel syntheses and design approaches of disruptive and innovative materials and NextGen devices that meet the chemical and physical requirements for reducing global warming through sustainable development. Furthermore, insights and lessons learned would be strongly transferable to other emerging materials for Photo- and Electrochemical Fuel Synthesis.