The abstract looks simple enough? They played with some chemicals / catalysts, and have demonstrated a prototype where they made a "Solar Panel" that turns water (H2O) into 2H2 + O2... aka Hydrogen + Oxygen. The measured efficiency was 13.8%, less efficient than an electric solar panel (20% to 25% efficiency), but possibly the most efficient solar -> hydrogen design discussed so far.

Consider a 25% efficient solar panel -> 50% electrical efficiency to convert H2O into H2 + O2 == 12.5% total efficiency (and a 25% efficient solar panel is a high-end panel). So this design discussed is probably better than the status quo.

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There are internet flame wars over the future of energy and energy storage.

Lithium Ion batteries are one form. Hydrogen is being proposed as a fuel of the future (with Japan showing off Hydrogen torches all over the Olympics earlier this year, as a lot of Japanese companies are pushing Hydrogen as a future fuel)

Some people didn't like that you could combine bog-standard 20% efficient photovoltaic panels with bog-standard 75% efficient electrolyzers to reach 15% efficiency of conversion of sunlight to hydrogen, and came up with a specialized single-step device...that is only 14% efficient. ;)