While it is not new news in the sense that the artificial leaf has been mentioned before, this MIT press release is based off of a new Science paper from the No

While it is not new news in the sense that the artificial leaf has been mentioned before, this MIT press release is based off of a new Science paper from the Nocera lab where, in contrast to the previous papers, this "leaf" does both hydrogen and oxygen generation in the same device. So the breakthrough here is that a tandem PV was used (to supply the necessary voltage for splitting water) and both hydrogen and oxygen evolution catalysts were integrated with the PV. The previous news had early versions of the device that used only a single junction PV. Thus, some external potential had to be applied for catalysis. Also, the device only had the oxygen evolving catalyst and relied on a buffer solution to supply the H+ ions. Therefore, the earlier versions of the device could not split water by itself when dropped into water. This new device can.