Water Reactivity in Electrified Interfaces: The Simultaneous Production of Electricity, Hydrogen, and Hydrogen Peroxide at Room Temperature

Abstract

Hygroelectric cells deliver hydrogen, hydrogen peroxide, and electric current simultaneously at room temperature from liquid water or vapor. Different cell arrangements allowed the electrical measurements and the detection and measurement of the reaction products by two methods each. Thermodynamic analysis shows that water dehydrogenation is a non-spontaneous reaction under standard conditions, but it can occur within an open, non-electroneutral system, thus supporting the experimental results. That is a new example of chemical reactivity modification in charged interfaces, analogous to the hydrogen peroxide formation in charged aqueous aerosol droplets. Extension of the experimental methods and the thermodynamic analysis used in this work may allow the prediction of interesting new chemical reactions that are otherwise unexpected. On the other hand, this adds a new facet to the complex behavior of interfaces. Hygroelectric cells shown in this work are built from commodity materials, using standard laboratory or industrial processes that are easily scaled up. Thus, hygroelectricity may eventually become a source of energy and valuable chemicals.

Hydrocarbon Degradation by Contact with Anoxic Water Microdroplets

“…The existence of electrons that come about accompanying the formation of •OH at the gas–water interface of the microdroplets has been supported by the unique reduction reaction over water microdroplets. ,,,− Formation of H 2 has been suggested to be the fate of the electrons pulled from the water microdroplet interface. , To verify the possible formation of H 2 at the water–oil microdroplet interface, we initially evacuate the fresh emulsion for 10 min, which can exclude interference from potentially dissolved H 2 in water (Figure a, see the materials for the detailed procedure). The absence of dissolved H 2 in the fresh evacuated emulsion was further confirmed by the molecular hydrogen test kit that can detect dissolved H 2 at ppb level (Movies S1 and S2).…”

The emerging chemistry of self-electrified water interfaces

“…Nguyen et al 129 proposed that hydrogen is the reduced coproduct of hydrogen peroxide formation and asked for its experimental verification that was recently published, 130 analogous to hygroelectricity. 131 A different mechanism proposed by Colussi identifies the mechanical energy required for droplet formation as the energy source for hydrogen peroxide formation. 132…”

“…Although the literature is full of different names and acronyms for water-driven energy conversion devices, HV harvesters can be categorized into three primary types: hygroelectric generators, which generate electricity through the sorption/desorption of water vapor or liquid; 131,147 evaporation-driven generators, which convert the latent heat of vaporization into electricity without the need for additional mechanical work; 148,149 and generators that harvest energy due to streaming potentials at liquid water–solid interfaces. 150,151 On the other hand, given the similarities and tenuous boundaries between each phenomenon, more than one mechanism can happen concurrently for a given device.…”

“…The first experimental demonstration of simultaneous hydrogen and H 2 O 2 production in a water–solid interfacial reaction was carried out using hygroelectric cells. 131 In this case, the authors presented a thermodynamic analysis showing how this reaction, which is non-spontaneous under standard conditions, takes place in an open system showing electric potential gradients.…”

Contact-electro-catalysis (CEC)

“…reactions, [40][41][42][43][44] further verifying the feasibility of catalyzing chemical reactions through the CE effect. In this context, contact-electro-catalysis (CEC) has been proposed as a bridging concept that connects CE with mechanochemistry, and has been demonstrated to be a significant supplement to existing catalytic strategies.…”