Technically this is about evolving oxygen gas from water more than it is about the hydrogen end of the electrocatalytic reaction. Since this is a cathode (2H+ + 2e- -> H2 gas) vs. anode process (2H2O -> 4H+ + 4e- + O2) linked up by a wire to close the circuit, you have two chemical processes to manage. The oxygen-evolving one tends to be slower, i.e. rate limiting. For an overview:
https://sci-hub.se/10.1039/c9cs00607a
Song, et al. (2020). "A review on fundamentals for designing oxygen evolution electrocatalysts." Chemical Society Reviews.
>"Therefore, the OER is the key process that governs the overall efficiency of electrochemical water splitting. To date, IrO2 and RuO2 have been state-of-the-art OER catalysts. However, both of them are made of precious metals and the cost is high. Therefore, it is imperative to seek low-cost alternative materials that can effectively reduce the kinetic limitation of OER and improve the efficiency of water splitting."
So, they discovered that the catalyst used at the OER end has some light-activation property, which is pretty interesting, i.e. they discovered a kind of photovoltaic electrocatalyst. Whether it will prove to be industrially useful is anyone's guess. There are similar systems but they're not very practical (i.e. they require high-energy UV):
https://physicsworld.com/a/light-activated-catalysts-make-ne...
As far as hydrogen-from-water tech, again it has three plausible large-scale cleantech industrial uses: ammonia from atmospheric N2, reduction of iron ore to sponge iron, and methane (and plausibly jet fuel) production from atmospheric CO2.
https://sci-hub.se/10.1039/c9cs00607a
Song, et al. (2020). "A review on fundamentals for designing oxygen evolution electrocatalysts." Chemical Society Reviews.
>"Therefore, the OER is the key process that governs the overall efficiency of electrochemical water splitting. To date, IrO2 and RuO2 have been state-of-the-art OER catalysts. However, both of them are made of precious metals and the cost is high. Therefore, it is imperative to seek low-cost alternative materials that can effectively reduce the kinetic limitation of OER and improve the efficiency of water splitting."
So, they discovered that the catalyst used at the OER end has some light-activation property, which is pretty interesting, i.e. they discovered a kind of photovoltaic electrocatalyst. Whether it will prove to be industrially useful is anyone's guess. There are similar systems but they're not very practical (i.e. they require high-energy UV):
https://physicsworld.com/a/light-activated-catalysts-make-ne...
As far as hydrogen-from-water tech, again it has three plausible large-scale cleantech industrial uses: ammonia from atmospheric N2, reduction of iron ore to sponge iron, and methane (and plausibly jet fuel) production from atmospheric CO2.