Recently, Professor Zong Xu’s team from the Clean Energy Research Center for Ships, under the Marine Engineering College, has made significant progress in solar-driven "green hydrogen" production. Their research, titled Depressing Charge Recombination in Hybrid Perovskites by Introducing Dynamic Electron/energy Relay Couple Towards Enhanced Photocatalytic Hydrogen Production, was published in Energy & Environmental Science (impact factor 32.4). This marks the first research paper by our university, as the sole corresponding institution, to be published in this prestigious journal. Energy & Environmental Science is globally recognized as a top-tier journal in the field of energy and environmental science, with a focus on critical and high-quality research in energy conversion and storage, alternative fuel technologies, and environmental science. It ranks first among over 400 journals in the field, boasting a 2024 impact factor of 32.4 and a five-year average impact factor of 34.5.

Reducing greenhouse gas emissions from ships is an essential requirement for the shipping industry to address climate change. Converting renewable energy into clean and efficient hydrogen energy for applications in the traditionally fossil fuel-reliant maritime industry represents an ideal pathway for achieving emission reduction. Solar energy, as the most abundant renewable energy source on earth, provides an optimal route for hydrogen production via semiconductor photocatalysis. A key focus of research in this field is the development of strategies to enhance the separation and transport of photogenerated charges in semiconductors to enable efficient photocatalytic hydrogen production.

Organic-inorganic hybrid perovskite (OIHP), with its unique optoelectronic properties, serves as an ideal carrier for photocatalytic hydrogen evolution reactions. However, severe recombination of photogenerated charges significantly limits the hydrogen evolution performance of OIHP-based photocatalysts. Thus, developing strategies to promote the separation and transport of photogenerated charges in OIHPs is critical to achieving efficient solar energy conversion. In recent years, strategies such as cocatalyst engineering, electronic structure engineering, and their combinations have been employed to enhance charge separation and transport in OIHPs. Nevertheless, the solar-to-hydrogen (STH) energy conversion efficiency achieved in related studies remains well below theoretical values.

In this work, the research team introduced a dynamic Cu/(CuI₂)⁻ electron/energy relay station into the MAPbI₃ perovskite system, significantly depressing photogenerated charge recombination in the MAPbI₃ photocatalyst and markedly improving its photocatalytic hydrogen production activity. The study revealed that (CuI₂)⁻ in the reaction solution effectively captured photogenerated electrons from MAPbI₃, forming metallic Cu in situ as an electron/energy storage medium. This mechanism depressed photogenerated charge recombination and achieved photon energy storage. The in situ-generated metallic Cu subsequently reacted with hydroiodic acid (HI) to release stored solar energy, enabling a decoupled dark-state hydrogen generation reaction analogous to the dark reduction processes in natural photosynthesis. Furthermore, metallic Cu acted as a cocatalyst for the hydrogen evolution reaction (HER), facilitating the reduction of protons by photogenerated electrons from MAPbI₃ to produce hydrogen. By further introducing platinum (Pt) as an HER cocatalyst, the dark-state chemical hydrogen generation reaction and the light-driven proton reduction reaction were accelerated. As a result, the photocatalytic hydrogen evolution activity of the MAPbI₃ system was enhanced by 2334 times, achieving an STH conversion efficiency of up to 5.25%. This work provides a novel strategy for the development of efficient OIHP-based solar hydrogen production systems.

The first author of this paper is Liu Jiaqi, a 2021 doctoral student from Marine Engineering College of Dalian Maritime University. Researcher Gao Yuying from Dalian Institute of Chemical Physics contributed to the study's reaction mechanism analysis. This work was supported by the National Natural Science Foundation of China, Liaoning Revitalization Talent Program, and the Leading Talent Program of Dalian Maritime University.