A Bias‐Free, Stand‐Alone, and Scalable Photovoltaic–Electrochemical Device for Solar Hydrogen Production

Although photovoltaic–electrochemical (PV–EC) water splitting is likely to be an important and powerful tool to provide environmentally friendly hydrogen, most developments in this field have been conducted on a laboratory scale so far. In order for the technology to make a sizeable impact on the energy transition, scaled up devices must be developed. Here a scalable (64 cm 2 aperture area) artificial PV–EC device composed of triple‐junction thin‐film silicon solar cells in conjunction with an electrodeposited bifunctional nickel iron molybdenum water‐splitting catalyst is shown. The device shows a solar to hydrogen efficiency of up to 4.67% (5.33% active area, H 2 production rate of 1.26 μmol H 2 /s) without bias assistance and wire connection and works for 30 min. The gas separation is enabled by incorporating a membrane in a 3D printed device frame. In addition, a wired small area device is also fabricated in order to show the potential of the concept. The device is operated for 127 h and initially 7.7% solar to hydrogen efficiency with a PV active area of 0.5 cm2 is achieved.