Atomic Ir-doped NiCo layered double hydroxide as a robust bifunctional catalyst for highly efficient and durable overall water splitting.

Water splitting in a photoelectrochemical cell, which converts sunlight into hydrogen energy, has recently received intense research. Silicon is suitable as a viable light-harvesting material for constructing such cell; however, there is a need to improve its stability and explore a cheap and efficient cocatalyst. Here we fabricate highly efficient and stable photocathodes by integrating crystalline MoS catalyst with ∼2 nm AlO protected np-Si. AlO acts as a protective and passivative layer of the Si surface, while the sputtering method using a MoS target along with a postannealing leads to a vertically standing, conformal, and crystalline nano-MoS layer on AlO/np-Si photocathode. Efficient (0.4 V vs RHE onset potential and 35.6 mA/cm saturated photocurrent measured under 100 mA/cm Xe lamp illumination) and stable (above 120 h continuous water splitting) photocathode was obtained, which opens the door for the MoS catalyst to be applied in photoelectrochemical hydrogen evolution in a facile and scalable way.

No abstract

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.

When a Si photocathode is used in a photoelectrochemical cell for H2 production, an open nanostructure capable of enhanced light absorption, low surface recombination, and being fully protected by thin protective layer is highly desirable. Here, we explored a highly stable and efficient multi-crystalline (mc) n+p silicon photocathode. A pyramid-like surface nanostructure on mc-Si wafer was fulfilled through a two-step metal-catalyzed chemical etching process, and then a n+p junction photocathode protected by a thin Al2O3 layer was constructed. The photocathode exhibits a high stability of continuous photoelectrochemical H2 production for above 100 h after a thin layer of Al2O3 is coated on its surface, and its energy conversion efficiency can be up to 6.8% after Pt loading, due to the lowered surface light reflection, increased surface area and minority carrier life time on the electrode surface.