An artificial photosynthetic device, or called artificial leaf, mimics nature’s photosynthesis, takes sunlight and splits water into H2 and O2. Once abundant and low-cost solar fuels of H2 is produced as a universal energy carrier, we can use it to convert synthetic fuels, upgrade bio-fuel feedstock, improve combustion and produce ammonia. However, achieving such an efficient and flexible artificial leaf is not trivial, particularly due to the instability of efficient semiconductor/liquid interfaces: All technologically important semiconductors so far like Si and GaAs photocorrode. Although protective coatings are not prevalent in solid-state materials research, they are essential in the field of (photo-)electrochemistry.
In this talk, I will first discuss recent breakthroughs in protective coatings as a stabilization strategy. With protective coating strategies, a 10% efficient water-splitting artificial leaf has been demonstrated. With modeling-inspired materials design, I will show a viable pathway beyond 20% efficiencies. Finally, I will discuss needs for basic understanding of photocatalytic processes at solid/liquid interfaces, particularly using operando spectroscopy. Understanding the change-transfer rates and selectivity of solid/liquid interfaces promise cost-effective particle-based photocatalyst devices. We call them artificial chloroplast as the next-generation artificial leaf.