Photoelectrochemical water splitting in separate oxygen and hydrogen cells.

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.

Tunable touch sensor and combined sensing platform: toward nanoparticle-based electronic skin.

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.