Water. In a conventional CO2 electrolyzer (electricity + CO2 -> CO + O2) where CO2 is dissolved in water (plus salt) H2 is the standard byproduct per H2O + electricity -> H2 + O2. The concept of CO2+H2O directly into H2 + CO is neither novel nor useful, as dedicated green-H2 production is more efficient.
This is an example of 'meh' level work being puffed up.
This is an example of 'meh' level work being puffed up.