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# Chalmers team links donor and acceptor polymers for more stable photocatalytic hydrogen production
- URL: https://research-pop.com/chalmers-team-links-donor-and-acceptor-polymers-for-more-stable-photocatalytic-hydrogen-production/
- Published: 2026-10-19T14:49:55.000Z
- Updated: 2026-10-19T14:49:55.000Z
- Author: ResearchPOP

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/10/Screenshot-2026-10-19-at-16.45.31.png)

Source: [https://advanced.onlinelibrary.wiley.com/doi/10.1002/aenm.71708](https://advanced.onlinelibrary.wiley.com/doi/10.1002/aenm.71708?ref=research-pop.com)

## At a glance

Organic donor–acceptor nanoparticles can absorb sunlight and generate charges for hydrogen production, but their performance depends on how the two polymers arrange inside each particle. A Chalmers University of Technology-led team tackles that structural sensitivity by covalently connecting the PBDB-T donor and PYT acceptor into a block copolymer, PBDB-T-b-PYT.

Under the standard comparison conditions, the block-copolymer nanoparticles produce 239 µmol of hydrogen per hour, approximately four times the rate of a physical donor–acceptor blend. They retain 94% of their initial hydrogen-evolution rate over four 10-hour cycles, with ascorbic acid replenished between cycles. Three independently synthesized polymer batches show less than 4% variation in activity.

Optimizing the nanoparticle and ascorbic-acid concentrations raises hydrogen production above 450 µmol h⁻¹. The experiments use Pt as a cocatalyst and ascorbic acid as a sacrificial electron donor.

## Background

Organic semiconductors offer considerable freedom in photocatalyst design because their molecular structures can be adjusted to change light absorption, energy levels and interactions with neighbouring materials. Combining an electron donor with an electron acceptor creates an interface that can help separate the excited states generated by light.

In these materials, light initially produces an exciton: an electron and a hole held together by electrostatic attraction. To support a chemical reaction, that pair must separate, and the resulting charges must reach reactive sites before recombining. In the system studied here, electrons reach Pt sites that catalyse hydrogen evolution, while ascorbic acid consumes the holes.

The arrangement of donor and acceptor within a nanoparticle therefore matters. Close contact supports exciton separation, while connected pathways help charges travel towards the surface. Physical blends rely on separate polymer chains assembling into a useful structure during nanoparticle preparation. Changes in processing or subsequent chain rearrangement can alter that structure and its performance.

Covalently connecting the two polymers offers another way to control their relationship. The researchers prepare PBDB-T-b-PYT through sequential polymerization, targeting a donor-to-acceptor mass ratio near 1:1\. Miniemulsion processing with the cationic surfactant C₁₆TAB then produces water-dispersed nanoparticles for comparison with the individual polymers and their physical blend.

## Research question

Can a covalent connection between donor and acceptor constrain compositional rearrangement while preserving effective charge separation and transport? Does that molecular architecture improve hydrogen production, operational stability and reproducibility across independently prepared samples?

The study follows these questions from polymer synthesis and nanoparticle composition to excited-state dynamics, photocatalytic performance and tests across particle sizes and operating conditions.

## Inside the study

### Building a connected donor–acceptor architecture

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/10/Screenshot-2026-10-19-at-16.45.40.png)

**Figure 1** introduces the block-copolymer structure and its optical and electrochemical properties. PBDB-T-b-PYT has a weight-average molecular mass of 33.8 kg mol⁻¹ and a dispersity of 2.1\. Its donor and acceptor components provide complementary absorption across the visible and into the near-infrared region.

Emission measurements offer an early indication that the connected components interact. With 564 nm excitation in dilute chloroform, the block copolymer emits at 818 nm, close to the 825 nm emission of PYT. The PBDB-T emission feature around 670 nm is absent. The authors interpret this suppression as evidence of efficient intramolecular quenching following donor excitation, then investigate the underlying excited-state processes in nanoparticles.

### Following excited-state transfer

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/10/Screenshot-2026-10-19-at-16.45.48.png)

**Figure 2** compares block-copolymer and physical-blend nanoparticles with similar mean diameters: 87 ± 6 and 81 ± 6 nm, respectively. At 564 nm excitation and an active-material concentration of 0.01 mg mL⁻¹, fluorescence quenching exceeds 80% in the block particles, compared with 54% in the blend. Selective excitation of the acceptor also supports more effective hole transfer in the covalently connected architecture.

Transient-absorption measurements add a time-resolved view. Following 550 nm excitation, the block particles show a donor-to-acceptor spectral change within approximately 5 ps. At a probe wavelength of 630 nm, about 13% of the initial transient-signal magnitude remains after 2 ns, compared with approximately 3% in the blend and 4% in PBDB-T particles.

These percentages describe the persistence of the measured transient signal. Interpreted alongside the emission and kinetic measurements, they support the authors’ account of improved charge generation and longer-lived excited-state features.

### Mapping composition within the particles

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/10/Screenshot-2026-10-19-at-16.45.59.png)

**Figure 3** examines whether the molecular connection changes nanoscale composition. STEM-EDX uses nitrogen as a marker for PYT because the acceptor contains nitrogen and PBDB-T does not. At a pixel resolution of 4 × 4 nm², both nanoparticle types show nitrogen throughout their projected cross-sections, without a distinct core–shell arrangement.

The compositional profiles are more closely correlated in the block particles, consistent with a somewhat more uniform acceptor distribution and constrained nanoscale variation. These two-dimensional measurements support the structural picture, while the optical experiments establish how the different architectures behave after excitation.

### Connecting charge behaviour to hydrogen production

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/10/Screenshot-2026-10-19-at-16.46.05.png)

**Figure 4** brings the structural and photophysical comparisons into a photocatalytic test. The standard experiment uses 0.75 mg of nanoparticles in 30 mL water, 3 wt.% Pt and 0.1 M ascorbic acid. The reported illumination is 100 mW cm⁻² over 10 cm², with operation at 6 °C and 1.2 kPa.

PBDB-T-b-PYT produces hydrogen at 239 µmol h⁻¹, compared with 61 µmol h⁻¹ for the 1:1 physical blend. Expressed using the paper’s area- and mass-normalized metric, the corresponding rates are 32 and 8.1 mmol cm⁻² g⁻¹ h⁻¹.

The block particles achieve apparent quantum yields of approximately 10% at 500, 600, 650 and 700 nm. Their photocurrent–intensity exponent is 0.90, compared with 0.71 for the blend, providing another comparison of the two systems’ response to illumination.

Measured photodeposited Pt contents are nearly identical—2.6 ± 0.1 and 2.7 ± 0.1 wt.%—so a difference in total cocatalyst loading does not explain the approximately fourfold activity gap.

### Testing whether the advantage persists

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/10/Screenshot-2026-10-19-at-16.46.17.png)

**Figure 5** follows hydrogen evolution over four 10-hour cycles, with consumed ascorbic acid replenished after each interval. After 40 hours, the block-copolymer nanoparticles retain 94% of their initial rate, while the physical blend retains 69%.

The block particles also preserve their absorption and emission profiles, whereas the blend develops pronounced spectral changes. The authors associate those changes with less stable internal morphology and propose that covalent linkage limits the donor–acceptor rearrangement available to separate polymer chains.

The article additionally reports more than 95% rate retention after 96 hours under LED illumination. This is a separate operating condition from the four-cycle comparison.

### Bringing the mechanism together

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/10/Screenshot-2026-10-19-at-16.46.23.png)

**Figure 6** presents the authors’ working model. Covalent linkage keeps the donor and acceptor connected at the molecular level and restricts their independent rearrangement. The resulting nanoscale organization accompanies stronger fluorescence quenching, more persistent transient features and higher hydrogen-evolution activity.

The model connects molecular architecture, compositional mapping, excited-state measurements and catalytic performance. Each method contributes a different part of the argument: microscopy constrains the spatial picture, spectroscopy follows the response to light, and hydrogen measurements establish the chemical outcome.

### Exploring size, reproducibility and operating conditions

![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/10/Screenshot-2026-10-19-at-16.46.30.png)

**Figure 7** tests whether the improvement extends beyond one nanoparticle preparation. Block-copolymer particle diameters range from 29 to 114 nm. Activity is comparable for particles above approximately 70 nm, but falls from about 30 to 20 mmol cm⁻² g⁻¹ h⁻¹ at smaller sizes. The authors associate this decline with reduced absorption, lower structural order and the greater surfactant demand of smaller particles.

Three independently synthesized polymer batches produce nanoparticles measuring 87–91 nm and an average hydrogen-evolution rate of 39 ± 1 mmol cm⁻² g⁻¹ h⁻¹. The variation is below 4%, supporting reproducibility across the tested batches.

Reaction conditions also change the outcome. With 0.2 M ascorbic acid, 3 wt.% Pt and 25 µg mL⁻¹ nanoparticles, the block system produces 287 µmol h⁻¹, corresponding to 38 mmol cm⁻² g⁻¹ h⁻¹. Reducing the nanoparticle concentration to 12.5 µg mL⁻¹ improves light penetration and raises production above 450 µmol h⁻¹ and the normalized rate above 120 mmol cm⁻² g⁻¹ h⁻¹.

At the same lower particle concentration, the physical blend produces 74 µmol h⁻¹, or 20 mmol cm⁻² g⁻¹ h⁻¹. The paper reports a solar-to-chemical hydrogen efficiency of 0.98% for the optimized block system. Because ascorbic acid supplies sacrificial reducing equivalents, that value belongs to the stated reaction system and should be interpreted with its chemical inputs included.

## Takeaways and outlook

The study connects polymer architecture with three practical outcomes: hydrogen-production rate, operational retention and batch reproducibility. Covalently joining donor and acceptor constrains their independent rearrangement while maintaining the interactions needed for light-driven charge separation.

The strongest evidence comes from the agreement among compositional mapping, optical measurements and photocatalytic comparisons. Similar particle sizes and Pt contents help focus the comparison on the donor–acceptor architecture, while tests across particle sizes and independently synthesized batches broaden the result beyond a single preparation.

The authors identify other donor–acceptor combinations, lower precious-metal requirements and closer analysis of morphology during extended operation as directions for further development. The present work establishes a molecular strategy for improving sacrificial-donor-assisted hydrogen evolution.

## About the researchers

Alexandre Holmes and Qiaonan Chen, both at Chalmers University of Technology, contributed equally as first authors. C. Moyses Araujo, affiliated with Karlstad University and Uppsala University, and Ergang Wang, affiliated with Chalmers University of Technology and Zhengzhou University, are the corresponding authors.

The team also includes Rafael Bicudo Ribeiro, affiliated with Chalmers University of Technology and the University of São Paulo; Xiaoman Bi, affiliated with Chalmers University of Technology and Zhengzhou University; and Márcio T. do N. Varella of the University of São Paulo.

Leandro R. Franco, Soumi Roy, Linnea Lind, Mateus Bergami, Mathis Mortensen Brette, Lunjie Zeng, Eva Olsson and Bo Albinsson are affiliated with Chalmers University of Technology.

## Original research

Alexandre Holmes; Qiaonan Chen; Rafael Bicudo Ribeiro; Leandro R. Franco; Soumi Roy; Linnea Lind; Xiaoman Bi; Mateus Bergami; Mathis Mortensen Brette; Lunjie Zeng; Eva Olsson; Bo Albinsson; Márcio T. do N. Varella; C. Moyses Araujo; Ergang Wang. “Covalently Locked Donor–Acceptor Block Copolymer Nanoparticles Enable Efficient, Stable and Reproducible Photocatalytic Hydrogen Evolution.” *Advanced Energy Materials*, first published 18 October 2026\. DOI: 10.1002/aenm.71708.

Original paper: [https://doi.org/10.1002/aenm.71708](https://doi.org/10.1002/aenm.71708?ref=research-pop.com)

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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.