Photocatalytic Water Splitting with Van der Waals Heterostructures

Photocatalytic water splitting harnesses solar energy to drive the decomposition of water into hydrogen and oxygen, offering a carbon-neutral route to clean fuel. Van der Waals heterostructures assemble atomically thin layers of two-dimensional materials through weak interlayer forces, enabling precise control of band alignment, light absorption and charge transfer across interfaces. By selecting complementary semiconducting layers—such as transition metal dichalcogenides, group-IV compounds or nitrides—researchers can engineer type-II or Z-scheme architectures that promote efficient separation of photogenerated carriers and enhance redox activity. These nanoscale assemblies exhibit tunable bandgaps, large active surface areas and intrinsic built-in electric fields that mitigate electron–hole recombination. As hydrogen demand escalates worldwide, van der Waals heterostructures are emerging as a versatile platform for scalable, high-performance photocatalysts with the potential to transform solar-to-hydrogen technologies.

Research from Nature Portfolio

Recent studies have explored heterobilayers of two-dimensional GeC and SiC, demonstrating dynamically stable structures that maintain negative interlayer binding energy and non-negative phonon frequencies. Depending on stacking arrangement, these heterobilayers exhibit direct bandgaps ranging from approximately 1.98 eV to 2.69 eV, with absorption coefficients exceeding 10⁶ cm⁻¹. Application of biaxial strain enables continuous tuning of the bandgap and alignment of redox potentials, ensuring thermodynamically favourable conditions for water splitting across UV to visible wavelengths. Under moderate tensile or compressive strain (±6 %), two configurations sustain sufficiently high kinetic overpotentials for hydrogen evolution while preserving interface stability.

Foundational work on transition metal dichalcogenide/graphene-like ZnO heterostructures has revealed type-II band alignment at MoS₂/ZnO and WS₂/ZnO interfaces, generating sizeable built-in electric fields that drive photogenerated electrons and holes to separate across the interface. These assemblies display strong optical absorption throughout the visible and near-infrared spectrum, highlighting their suitability for broadband solar harvesting. The weak van der Waals interaction preserves the intrinsic properties of each monolayer while facilitating ultrafast charge transfer, reducing recombination losses and enhancing quantum efficiency.

Photocatalytic Water Splitting with Van der Waals Heterostructures publication trend

The graph below shows the total number of articles in photocatalytic water splitting with van der waals heterostructures across all publications each year (not limited to Nature Index journals).

Technical terms

Photocatalytic water splitting: A process in which a semiconductor catalyst uses light energy to drive the redox reactions that convert water into hydrogen and oxygen.

Van der Waals heterostructure: A stack of two-dimensional materials held together by weak van der Waals forces, allowing independent tuning of each layer’s electronic properties.

Type-II band alignment: An arrangement in which the conduction band minimum and valence band maximum reside in different materials, promoting spatial separation of electrons and holes.

Z-scheme photocatalyst: A dual-junction system that mimics natural photosynthesis, using sequential light-driven steps to achieve high redox potentials and efficient charge separation.

Biaxial strain engineering: The application of uniform tensile or compressive stress in two in-plane directions to adjust a material’s electronic band structure and catalytic activity.

References

1. Electronic and optical properties of heterostructures based on transition metal dichalcogenides and graphene-like zinc oxide. Scientific Reports (2018).
2. Strain-tunable III-nitride/ZnO heterostructures for photocatalytic water-splitting: A hybrid functional calculation. APL Materials (2020).
3. Band Bending Mechanism in CdO/Arsenene Heterostructure: A Potential Direct Z-scheme Photocatalyst. Frontiers in Chemistry (2021).
4. Superior tunable photocatalytic properties for water splitting in two dimensional GeC/SiC van der Waals heterobilayers. Scientific Reports (2021).