Photodetectors are the “eyes” of modern electronic systems, playing a vital role in fields ranging from optical communication and imaging to sensing. As technology advances, there is a growing demand for photodetectors that are not only highly sensitive but also capable of detecting a broad spectrum of light, responding rapidly, and distinguishing complex optical information. However, traditional photodetectors often face inherent limitations, such as low light absorption efficiency in thin materials, slow response speeds due to carrier trapping, and limited spectral ranges dictated by material bandgaps.

This article collection features papers published in Environmental Surfaces and Interfaces since 2023 on the theme of materials‑driven environmental pollutant removal. It focuses on the development of novel materials and their practical applications in environmental pollutant remediation. All articles are freely available for reading.

A new formulation of CO₂ foams could help address one of the energy industry’s main challenges, specifically regarding the injection of CO₂ underground: controlling CO₂ mobility in reservoir porous media. This advancement has the potential to improve reservoir sweep, enhance oil recovery, and increase geological CO₂ retention. A recent study demonstrates that a polymer-reinforced CO₂ foam can multiply the flow resistance of CO₂, preventing it from moving inefficiently through the reservoir.

Oxford researchers have demonstrated the first wireless quantum key distribution (QKD) system in the ultraviolet-C (UV-C) band, enabling secure wireless communication in direct sunlight. Published in Optica Quantum, the system uses UV-C micro-LEDs and single-photon detectors to operate in the "solar-blind" spectrum, achieving secure key rates over 1 Mbit/s with minimal ambient noise. Future work will focus on outdoor daylight testing and extending the communication range.

A multi-institutional research team reviews progress in CO₂-involved organic synthesis over the past five years. By organizing reactions according to C-C, C-N, and C-O bond formation, the review highlights the growing role of photochemistry and electrochemistry in converting CO₂ into value-added organic products.

Optical computing is attracting strong interest because light can carry and process information at extremely high speed while consuming less energy than many electronic approaches. In principle, optical systems can accelerate demanding tasks such as artificial intelligence inference, image processing, scientific simulation, and high-bandwidth signal processing. However, most proposed optical processors still depend on electronic memory to hold intermediate data. Each time information is converted between light and electronics, the system pays a penalty in speed, energy, and complexity.

Long-term diabetes management requires continuous blood glucose monitoring to detect abnormalities early and intervene in time. However, conventional fingertip blood sampling is both painful and inconvenient, while most continuous glucose monitoring (CGM) products currently available on the market rely on biological enzymes — requiring regular replacement, incurring higher costs, and demanding stringent storage conditions. A research team at The Hong Kong Polytechnic University (PolyU) has developed an enzyme-free, wearable, acoustically readable microneedle patch “ARMPatch”. Once applied to the skin, it can be read by a standard ultrasound probe to continuously reflect changes in blood glucose levels.

Heating, Ventilation and Air Conditioning (HVAC) systems play a crucial role in smart building management, but their energy consumption is a significant concern. Prof. Shengwei WANG, Chair Professor in Building Energy and Automation and Otto Poon Charitable Foundation Professor in Smart Buildings in the Department of Building Environment and Energy Engineering at The Hong Kong Polytechnic University has designed a versatile framework to integrate AI into building automation systems to improve energy efficiency.