Engineered active pure water with reduced hydrogen bonds catalyzes itself in green energy production of oxygen and hydrogen evolution reactions

Noble metals, like platinum (Pt), palladium (Pd) and gold (Au), that possess special electronic configurations, are popularly used in renewable energy technologies of oxygen and hydrogen evolution reactions (OER and HER). Recently, approaches for renewable energies have focused on earth-abundant and cheap catalysts with different chemical compositions and structures. In this work, we propose an alternative strategy for OERs and HERs, focusing on water itself, utilizing Au-free condensed water (PAW-C) from heated trace Au-containing plasmon-activated water (PAW). Compared to active PAW, the electron-doping structure of PAW-C was reduced, while the degree of reduced hydrogen bonds (HBs) in PAW-C was enhanced. Encouragingly, compared to deionized water (DIW)-based 0.1 M KOH solutions, the measured current densities of OERs on a catalytic Pt electrode were significantly higher by average magnitudes of 45% and 23% for the PAW-C-based and PAW-based 0.1 M KOH solutions, respectively. Compared to the DIW-based 0.1 M H₂SO₄ solution, the measured current density of HER on a catalytic Pt electrode was significantly higher by an average magnitude of 20% for the PAW-C-based 0.1 M H₂SO₄ solution (an average higher magnitude of 15% for the PAW-based solution). Moreover, this proposed strategy was applicable to inert carbon and stainless steel electrodes for OERs. After aging for 3 days, the activity of the PAW-C of enhancing OERs was reduced by only ca. 5%. This fact indicates that its practical applications are promising. Active and stable PAW-C has emerged as a promising green solvent applicable to more-effective OERs and HERs.