Since their discovery in 2016, halide double perovskites that are based on combinations of monovalent and trivalent cations, have been thoroughly investigated as potential lead-free alternatives to lead halide perovskites. In a recent study published in Applied Physics Letters, researchers George Volonakis and Feliciano Giustino, considered applications beyond photovoltaics and found that the lead-free double perovskites Cs2BiAgCl6, Cs2BiAgBr6, Cs2SbAgCl6 and Cs2InAgCl6 may open new opportunities in solar-driven photocatalytic water splitting. Using first-principles calculations they report on the stability of different surface terminations of the newly synthesised double perovskites, and also report their absolute energy levels. The energy levels of Cs2BiAgCl6 and Cs2BiAgBr6 are matching the redox potential of water. While, Cs2SbAgCl6 and Cs2InAgCl6 could also be suitable for either hydrogen evolution or water evolution. Futher details are in the AIP journal feature article press release.