Solar water splitting provides a promising path for sustainable hydrogen production and solar energy storage. One of the greatest challenges towards large-scale utilization of this technology is reducing the hydrogen production cost. The conventional electrolyser architecture, where hydrogen and oxygen are co-produced in the same cell, gives rise to critical challenges in photoelectrochemical water splitting cells that directly convert solar energy and water to hydrogen. Here we overcome these challenges by separating the hydrogen and oxygen cells. The ion exchange in our cells is mediated by auxiliary electrodes, and the cells are connected to each other only by metal wires, enabling centralized hydrogen production. We demonstrate hydrogen generation in separate cells with solar-to-hydrogen conversion efficiency of 7.5%, which can readily surpass 10% using standard commercial components. A basic cost comparison shows that our approach is competitive with conventional photoelectrochemical systems, enabling safe and potentially affordable solar hydrogen production.

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In this paper, we present touch (or pressure) flexible sensors based on monolayer-capped nanoparticles (MCNPs) that are potentially inexpensive, could allow low-voltage operation, and could provide a platform for multifunctional applications. We show that modifying the mechanical and geometrical properties of the flexible substrates, on which the MCNP films are deposited, allows measuring a large span of loads ranging between tens of mg to tens of grams. All flexible sensors exhibited repeatable responses even after a large number of bending cycles. In addition, we show that modified platforms of those touch (or pressure) sensors allow precise detection and monitoring of environmental temperature and humidity. Relying on their superior characteristics, we were able to build an MCNP-based prototype allowing simultaneous detection and monitoring of multiple environmental parameters of touch (or pressure), humidity, and temperature. The excellent temperature (resolution higher than 1 °C and average error of ~5%) and relative humidity (resolution higher than 1% RH and average error of ~9%) sensitivities and the possibility to integrate those sensing abilities makes the suggested platform interesting for potentially inexpensive and low-voltage multifunctional electronic-skin applications.

Photoelectrochemical (PEC) water splitting offers an elegant approach for solar energy conversion into hydrogen fuel. Large-scale hydrogen production requires stable and efficient photoelectrodes and scalable PEC cells that are fitted for safe and cost-effective operation. One of the greatest challenges is the collection of hydrogen gas from millions of PEC cells distributed in the solar field. In this work, a separate-cell PEC system with decoupled hydrogen and oxygen cells was designed for centralized hydrogen production, using 100 cm 2 hematite (-Fe 2 O 3) photoanodes and nickel hydroxide (Ni(OH) 2) / oxyhydroxide (NiOOH) electrodes as redox mediators. The operating conditions of the system components and their configuration were optimized for daily cycles, and ten 8.3 h cycles were carried out under solar simulated illumination without additional bias at an average short-circuit current of 55.2 mA. These results demonstrate successful operation of a decoupled PEC water splitting system with separate hydrogen and oxygen cells.

Decoupled water splitting is a promising new path for renewable hydrogen production, offering many potential advantages such as stable operation under partial-load conditions, high-pressure hydrogen production, overall system robustness, and higher safety levels. Here, the performance of electrospun core/shell nickel/nickel hydroxide anodes is demonstrated in an electrochemical-thermally activated chemical decoupled water splitting process. The high surface area of the hierarchical porous electrode structure improves the utilization efficiency, charge capacity, and current density of the redox anode while maintaining high process efficiency. The anodes reach average current densities as high as 113 mA cm −2 at a working potential of 1.48 V RHE and 64 mA cm −2 at 1.43 V RHE , with a Faradaic efficiency of nearly 100% and no H 2 /O 2 intermixing in a membrane-free cell.

Decoupled water splitting in an electrochemical – thermally-activated chemical (E-TAC) cycle is a promising path for safe, efficient and competitive production of green hydrogen at scale. Here, we demonstrate the...

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<ul> <li>Large surface area porous electrodes prepared from electrospun Ni and Ni-Co fibers</li> <li>A Ni/Ni(OH)₂ core/shell structure produced by galvanic cycling in alkaline media</li> <li>Electrodes with improved current density and charge capacity </li> <li>High efficiency decoupled water splitting with Ni/Ni(OH)₂ redox mediator</li> </ul>