Photoelectrochemical Water Splitting Using Nanostructured ZnO Materials

Photoelectrochemical water splitting harnesses solar energy to drive the decomposition of water into hydrogen and oxygen using semiconductor photoelectrodes. Zinc oxide, a wide-bandgap n-type semiconductor, has attracted considerable attention due to its abundance, non-toxicity and excellent electron mobility. Nanostructuring ZnO into arrays of rods, trees, sheets or composite architectures increases surface area, enhances light absorption and shortens carrier pathways. Strategies such as doping, heterojunction formation, surface passivation and integration of plasmonic particles have been employed to extend optical response into the visible range, suppress charge recombination and improve interfacial charge transfer. Recent advances demonstrate that precise control of morphology, dopant distribution and interface chemistry can yield photoanodes with elevated photocurrent densities, incident photon-to-current efficiencies and solar-to-hydrogen conversion efficiencies, highlighting the potential of nanostructured ZnO for decentralised hydrogen production and sustainable energy systems.

Research from Nature Portfolio

Recent studies have shown that gradient nitrogen doping of ZnO nanorod arrays by ion implantation produces terraced band structures that extend absorption into the visible region while promoting directional charge separation, resulting in two orders of magnitude higher photocurrent under visible light. Another approach has combined gold nanoparticles and thin aluminium oxide passivation layers on ZnO nanorods to exploit surface plasmon resonance and suppress surface recombination, achieving over six-fold enhancement in solar-to-hydrogen efficiency. Work on flexible stainless-steel supported ZnO nanoflower and nanorod photoanodes has demonstrated that mechanical straining reorients nanostructures, leading to up to 2.5-fold increases in incident photon-to-current efficiency and improved durability, a promising route for bendable solar hydrogen devices.

Photoelectrochemical Water Splitting Using Nanostructured ZnO Materials publication trend

The graph below shows the total number of articles in photoelectrochemical water splitting using nanostructured zno materials across all publications each year (not limited to Nature Index journals).

Technical terms

Photoelectrochemical water splitting: A solar-driven process in which a semiconductor photoelectrode oxidises water at the anode and reduces protons at the cathode to produce hydrogen and oxygen.

Photoanode: The light-absorbing electrode in a PEC cell where water oxidation occurs, generating oxygen and holes.

Nanostructure: A material feature with dimensions on the nanometre scale that can enhance surface area, charge separation and light absorption.

Surface plasmon resonance (SPR): Collective oscillation of conduction electrons in metallic nanoparticles induced by incident light, enhancing local electromagnetic fields.

Incident photon-to-current efficiency (IPCE): Ratio of the number of charge carriers collected by the photoelectrode to the number of incident photons at a given wavelength.

Applied bias photon-to-current efficiency (ABPE): Measure of the overall solar-to-hydrogen conversion efficiency of a PEC cell under an applied voltage bias.

References

1. N Doping to ZnO Nanorods for Photoelectrochemical Water Splitting under Visible Light: Engineered Impurity Distribution and Terraced Band Structure. Scientific Reports (2015).
2. Synergistic Effect of Surface Plasmonic particles and Surface Passivation layer on ZnO Nanorods Array for Improved Photoelectrochemical Water Splitting. Scientific Reports (2016).
3. Investigation of Strain Effects on Photoelectrochemical Performance of Flexible ZnO Electrodes. Scientific Reports (2019).
4. Nanoscale ZnO/α‐Fe2O3 Heterostructures: Toward Efficient and Low‐Cost Photoanodes for Water Splitting. Small Science (2021).
5. Effect of Morphology and Plasmonic on Au/ZnO Films for Efficient Photoelectrochemical Water Splitting. Nanomaterials (2021).
6. Effect of Cu, Ni and Pb doping on the photo-electrochemical activity of ZnO thin films. RSC Advances (2019).