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A porous NiFe (oxy)hydroxide catalyst fabricated on n+pp+-Si/Ni/NiOx, which is converted from an electrodeposited NiFe oxysulfide, allows a silicon photoanode for water splitting to hit a record 5.1% efficiency with good stability of up to 135 h under 40 mA cm−2 in 1.0 M NaOH. [ABSTRACT FROM AUTHOR]

Designing a highly efficient and stable photoelectrochemical (PEC) tandem cell for unassisted solar water splitting is considered a promising approach for large-scale solar energy storage. To date, various tandem device configurations have been reported. However, the achievement of a solar-to-hydrogen conversion efficiency (ηSTH) of 10% is still full of challenges, due to the incompatibility between the two photoelectrode materials. Here, we report a highly efficient and stable photovoltaic (PV)–PEC tandem device composed of a dual Si photoelectrode and two series-connected ordinary Si PV cells. The dual-photoelectrode device consists of an n+np+-Si photocathode and p+pn+-Si photoanode, which allow back illumination from the Si substrate, spatially and functionally decoupling the optical absorption and the catalytic activity. By further employing a Ni protective layer together with a bifunctional Ni–Mo catalyst for both the Si photocathode and photoanode, the PV–PEC tandem cell can perform spontaneous water splitting without any applied bias. A high ηSTH of 9.8% with a stability of over 100 h was achieved in alkaline solution under parallel AM 1.5G 1 sun illumination. This work essentially allows a modular independent optimization of each component which can enhance the efficiency and stability of the PV–PEC cells. [ABSTRACT FROM AUTHOR]

Excellent photoelectrochemical activity was demonstrated for an easily prepared porous Ni-O/Ni/Si photoanode with an onset potential of 0.93 VRHE, a photocurrent of 39.7 mA cm−2 at 1.23 VRHE, an energy conversion efficiency of 3.2% and a stability above 100 h. [ABSTRACT FROM AUTHOR]

Stable and cost-effective catalysts with low kinetic overpotentials for both the anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER) are indispensable for the large-scale implementation of electrochemical water splitting. In this study, we developed an efficient, stable and bifunctional Ni–Co–S/Ni–Co–P bistratal electrocatalyst on Ni foam (NF) using simple electrodeposition methods. The efficient contact at the Ni–Co–P/NF interface along with the porous Ni–Co–S surface results in the superior electrocatalytic activity of the bistratal layer in a basic solution for both the OER and HER. Only −0.11 V vs. RHE is required at a current density of −20 mA cm−2 for the HER and 1.47 V vs. RHE at 50 mA cm−2 for the OER, significantly outperforming bare Ni–Co–S or Ni–Co–P on NF. Most crucially, when functioning as a bifunctional catalyst for overall water splitting, a small cell potential of 1.49 V can drive 10 mA cm−2 which can be sustained for more than two days. Subsequently, 10.8%-efficient overall solar water splitting was achieved when driven by three ordinary Si solar cells. Such a bistratal structure is expected to provide a new platform for the design of highly efficient, low-cost and durable catalysts for water electrolysis systems. [ABSTRACT FROM AUTHOR]

A combination of hydrogen passivation, electroless deposition of a Pt catalyst and coating a TiO2 protective layer leads to an unprecedented 11.5% energy conversion efficiency and one-week stability of an n+np+-Si photocathode for solar water splitting. [ABSTRACT FROM AUTHOR]

A combination of hydrogen passivation, electroless deposition of a Pt catalyst and coating a TiO 2 protective layer leads to an unprecedented 11.5% energy conversion efficiency and one-week stability of an n + np + -Si photocathode for solar water splitting.