Quantum mechanics

Engineering

Electrochemistry

Materials science

Layer (electronics)

Telecommunications

Computer science

Silicon

Chemical engineering

Physical chemistry

Mechanical engineering

Crystalline silicon

Physics

Nanotechnology

Organic chemistry

Oxygen

Degradation (telecommunications)

Limiting current

Chemistry

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Limiting

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Electrolyte

Optoelectronics

Photocathode

Nature Communications

The trade-offs between photoelectrode efficiency and stability significantly hinder the practical application of silicon-based photoelectrochemical devices. Here, we report a facile approach to decouple the trade-offs of silicon-based photocathodes by employing crystalline TiO 2 with graded oxygen defects as protection layer. The crystalline protection layer provides high-density structure and enhances stability, and at the same time oxygen defects allow the carrier transport with low resistance as required for high efficiency. The silicon-based photocathode with black TiO 2 shows a limiting current density of ~35.3 mA cm −2 and durability of over 100 h at 10 mA cm −2 in 1.0 M NaOH electrolyte, while none of photoelectrochemical behavior is observed in crystalline TiO 2 protection layer. These findings have significant suggestions for further development of silicon-based, III–V compounds and other photoelectrodes and offer the possibility for achieving highly efficient and durable photoelectrochemical devices.

Crystalline TiO2 protective layer with graded oxygen defects for efficient and stable silicon-based photocathode