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# Adelaide University-led team uses nickel single-atom sites to photoreform PLA into lactate and hydrogen
- URL: https://research-pop.com/adelaide-university-led-team-uses-nickel-single-atom-sites-to-photoreform-pla-into-lactate-and-hydrogen/
- Published: 2026-09-19T12:20:20.000Z
- Updated: 2026-09-19T12:20:20.000Z
- Author: ResearchPOP
- Tags: Environment, Energy

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/Screenshot-2026-09-19-at-13.42.25.png)

**Source**: [https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.78520](https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.78520?ref=research-pop.com)

## At a glance

An Adelaide University-led team placed isolated Ni–S₄ sites on CdS nanorods to photoreform poly(lactic acid), or PLA, into lactate and hydrogen. The single nickel atoms are coordinated by four sulfur atoms at the CdS surface, creating charge-polarized sites while retaining the light-absorbing semiconductor structure.

Under the concentrated alkaline conditions reported in the paper, the Ni–S₄/CdS catalyst produced H₂ at 41.74 mmol g⁻¹ h⁻¹. Pristine CdS reached 26.95 mmol g⁻¹ h⁻¹ in the same comparison. Analysis of the liquid phase showed that the carbon-containing products were directed mainly toward lactate.

Microscopy, X-ray absorption spectroscopy, optical measurements, electrochemistry, in situ observations and calculations connect this response with two roles of the isolated nickel sites. They help manage photogenerated charge carriers and create a polarized local environment that interacts with PLA-derived ester groups. The study brings hydrogen evolution and selective liquid-product formation together in one photocatalytic system.

## Background

PLA is a polyester made from repeating lactic-acid-derived units. Its backbone contains ester bonds that can be hydrolysed under alkaline conditions, making the polymer different from plastics with less reactive carbon–carbon backbones. This chemical structure creates an opportunity to recover its carbon as smaller oxygenated products.

Photoreforming couples that organic transformation with solar-fuel production. When a semiconductor absorbs light, electrons are promoted into higher-energy states and leave holes behind. The electrons can participate in proton reduction to form H₂, while the holes drive oxidation and rearrangement of the organic substrate. Efficient operation requires the two charge carriers to reach their respective reactants before they recombine.

CdS is a visible-light-responsive semiconductor that has been widely examined for photocatalytic H₂ evolution. Its performance can still be limited by rapid electron–hole recombination and by how reactants interact with its surface. Adding a small number of atomically dispersed metal sites offers a way to adjust both processes without covering the semiconductor with larger metal particles.

## Research question

Can isolated, charge-polarized Ni–S₄ sites on CdS nanorods improve the use of photogenerated charges while directing alkaline PLA photoreforming toward lactate and H₂? The researchers also examine how the local nickel coordination environment interacts with ester-containing species during the reaction.

## Inside the study

The team prepared CdS nanorods decorated with atomically dispersed nickel. Electron microscopy retains the rod-shaped morphology of the CdS support, while elemental mapping shows nickel distributed across the material rather than concentrated in readily observed particles. The low-dimensional CdS structure provides the light-absorbing host for the isolated metal sites.

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/adfm78520-fig-0001-m.png)

Diffraction and photoelectron spectroscopy examine the crystalline framework and surface electronic states. Ni K-edge X-ray absorption measurements then focus on the local environment of nickel. The absence of a dominant Ni–Ni coordination contribution, together with the fitted first-shell structure, supports isolated nickel atoms coordinated by four sulfur atoms. The resulting site is described as Ni–S₄.

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/adfm78520-fig-0002-m.png)

This coordination is electronically asymmetric. Nickel and the surrounding sulfur atoms do not share charge evenly, producing a polarized local environment at the CdS surface. The authors connect that polarization with the ability of the site to interact with oxygen-containing groups derived from PLA.

Before illumination, PLA is treated in concentrated alkaline solution. The alkaline medium promotes cleavage of ester linkages and makes PLA-derived species more available to the photocatalyst surface. These solution conditions are part of the reaction design, linking polymer pretreatment with the subsequent light-driven steps.

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/adfm78520-fig-0003-m.png)

Under illumination, Ni–S₄/CdS produced H₂ at 41.74 mmol g⁻¹ h⁻¹. The corresponding rate for pristine CdS was 26.95 mmol g⁻¹ h⁻¹. The comparison shows how introducing a small number of isolated nickel sites changes the use of photogenerated electrons without replacing CdS as the main light absorber.

Liquid-phase analysis follows the carbon side of the reaction. Lactate is identified as the main liquid product from PLA under the reported conditions. The system consequently couples reduction at one side of the photochemical process, producing H₂, with transformation of the polymer-derived carbon into a recoverable oxygenated product.

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/adfm78520-fig-0004-m.png)

Optical and electrochemical measurements trace what happens to the photogenerated charges after the nickel sites are introduced. The reported photoluminescence lifetime increases from about 0.08 ns for CdS to about 0.47 ns for the Ni-containing material. Together with photocurrent and impedance measurements, this longer-lived response supports improved charge separation and transfer.

The proposed charge flow assigns complementary roles to the semiconductor and the isolated sites. CdS absorbs light and creates electron–hole pairs. The Ni–S₄ environment changes the local electronic structure and provides a route for charge redistribution, helping electrons remain available for H₂ evolution while holes participate in the organic transformation.

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/adfm78520-fig-0005-m.png)

In situ spectroscopic observations and calculations then examine the interaction with ester-containing species. The charge-polarized Ni–S₄ site strengthens the local interaction with the oxygen atoms of the ester group and changes the electronic distribution within the adsorbed molecule. In the authors’ mechanism, this activation makes the relevant bond transformations more accessible during conversion toward lactate.

The calculated adsorption configurations and reaction energetics are placed alongside the experimental charge-carrier measurements. This combined picture links the higher H₂ evolution rate and lactate-directed liquid chemistry to one atomic-scale modification: an isolated nickel centre coordinated within the sulfur environment of CdS.

## Takeaways and outlook

The study uses Ni–S₄ single-atom sites to connect two requirements of PLA photoreforming. The sites improve the management of photogenerated charges, supporting a higher H₂ evolution rate, and create a polarized environment for interacting with PLA-derived ester groups. The CdS nanorods remain responsible for light absorption, while the isolated nickel centres tune the surface reaction environment.

The alkaline pretreatment and photocatalytic stage also work as a connected sequence. Ester-bond cleavage makes the polymer-derived species available in solution, after which light-driven charge transfer supports H₂ formation and directs the liquid carbon toward lactate. Under the reported conditions, this gives 41.74 mmol g⁻¹ h⁻¹ H₂ alongside lactate as the main liquid product.

More broadly, the work shows how coordination at a single metal atom can influence both semiconductor charge dynamics and substrate activation. Similar site designs could be explored for other polyesters and oxygen-containing feedstocks, with the coordination environment adjusted to match the bonds involved in each transformation.

## About the researchers

Yu Yao (Adelaide University) is the first-listed author. Jinqiang Zhang (Adelaide University and the University of Western Australia) and Xiaoguang Duan (Adelaide University) are the corresponding authors.

The other authors are Panpan Zhang (Jiangsu University); Xi-lin Wu (Zhejiang Normal University); Tara Pukala, Yifei Wang and Shaobin Wang (Adelaide University); and Bernt Johannessen (Australian Nuclear Science and Technology Organisation).

## Original research

Yu Yao, Panpan Zhang, Jinqiang Zhang, Xi-lin Wu, Tara Pukala, Yifei Wang, Bernt Johannessen, Shaobin Wang and Xiaoguang Duan. “Charge-Polarized Ni–S₄ Single-Atom Sites Drive Selective Photoreforming of Poly(lactic acid) to Lactate and Hydrogen.” *Advanced Functional Materials*, published online 17 September 2026\. DOI: 10.1002/adfm.78520\. [Journal article](https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.78520?ref=research-pop.com) 

Open access publishing facilitated by Adelaide University, as part of the Wiley - Adelaide University agreement via the Council of Australasian University Librarians.

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## Research POP Notes

This article reflects the independent interpretation of the Research POP team and does not represent the views of the authors, their institutions or the journal. If you identify any inaccuracies or have concerns regarding the content, figures or attribution, please contact us at [team.researchpop@gmail.com](mailto:team.researchpop@gmail.com). We will review the matter promptly and make corrections or remove the relevant material where appropriate.