### Abstract: Activating Pure Copper for Efficient Hydrogen Evolution through Electroreduction-Driven Distorted Nanotwins Electrolysis of water for hydrogen production is a highly efficient and clean method, offering high purity hydrogen and excellent compatibility with renewable energy sources. In this process, catalysts play a crucial role by reducing the activation energy of the electrolysis reaction, thereby enhancing the rate and efficiency of hydrogen evolution. Platinum (Pt) and Iridium (Ir) are among the most effective catalysts for hydrogen evolution, but their high cost and limited availability significantly restrict their widespread application. Copper (Cu), on the other hand, is a promising alternative due to its low cost, high abundance, and excellent electrical conductivity. However, Cu's weak adsorption of hydrogen intermediates results in poor catalytic activity, typically limiting its use to current collectors rather than catalysts. Theoretical calculations suggest that introducing tensile strain and reducing the coordination number can effectively enhance Cu's adsorption of hydrogen intermediates. Addressing this challenge, a research team led by Professors Fang Fang and Sun Dalin from Fudan University's Department of Materials Science, in collaboration with researchers from Beijing University of Technology, Peking University, and Tianjin University, has developed a novel two-step synthesis strategy involving laser ablation and electrochemical reduction. This method has successfully produced pure Cu hydrogen evolution catalysts enriched with distorted nanotwins (DNTs-Cu), which exhibit superior catalytic activity and stability compared to commercial Pt/C catalysts under acidic conditions. The synthesis process begins with laser ablation, which creates Cu2O nanoparticles rich in grain boundaries. These nanoparticles are then electrochemically reduced to form Cu. During the electroreduction, the strong driving force of the electrochemical reaction rapidly reduces the fine Cu2O grains, preserving the lattice mismatch induced by grain boundaries. This results in the formation of a large number of distorted multiple twin structures in the reduced nano-Cu. Structural analysis reveals that these distorted twin structures interlock, creating strong and stable tensile strain and forming numerous atomic steps on the surface. The Cu-Cu bond length in DNTs-Cu increases from 2.158 Å in copper foil to 2.255 Å, and the coordination number decreases from 12 in copper foil to 9.5. The strong tensile strain and low coordination number in DNTs-Cu enhance the d-band center of the Cu catalytic sites, significantly improving the adsorption of hydrogen intermediates. In acidic electrolyte, DNTs-Cu demonstrates a remarkably low overpotential of just 61 mV at a current density of 10 mA cm-2, comparable to commercial Pt/C catalysts. At higher current densities exceeding 100 mA cm-2, DNTs-Cu surpasses the catalytic activity of commercial Pt/C. The stability of DNTs-Cu is also outstanding, with only a 2% performance decay after continuous operation at 500 mA cm-2 for 125 hours. Compared to previously reported Cu-based catalysts, DNTs-Cu exhibits superior catalytic activity and stability. The study highlights that electrochemical methods can generate stronger driving forces to produce strong and stable lattice strains, offering a new synthesis approach for metal functional materials. Additionally, the strategy of adjusting the adsorption energy of reaction intermediates by altering atomic coordination numbers and lattice strains provides a new paradigm for the design of efficient electrocatalysts. This breakthrough, published in the journal *Nature Materials* under the title "Electroreduction-Driven Distorted Nanotwins Activate Pure Cu for Efficient Hydrogen Evolution," opens new avenues for the development and application of low-cost, high-performance hydrogen evolution catalysts, potentially revolutionizing the field of renewable energy and green hydrogen production. **Article Information:** - Title: Electroreduction-Driven Distorted Nanotwins Activate Pure Cu for Efficient Hydrogen Evolution - Authors: Zhe Li#, Yueshuai Wang#, Hui Liu#, Yi Feng, Xiwen Du, Zhiheng Xie, Jihan Zhou*, Yang Liu, Yun Song, Fei Wang, Manling Sui, Yue Lu*, Fang Fang*, Dalin Sun* - Journal: *Nature Materials* - Year: 2025 - DOI: https://doi.org/10.1038/s41563-024-02098-2 ### Key Points: 1. **Catalyst Challenge**: Traditional Cu catalysts have poor hydrogen evolution activity due to weak adsorption of hydrogen intermediates. 2. **Innovative Synthesis**: A two-step method combining laser ablation and electrochemical reduction to create DNTs-Cu. 3. **Structural Enhancement**: Formation of distorted nanotwins and atomic steps, leading to strong tensile strain and reduced coordination numbers. 4. **Catalytic Performance**: DNTs-Cu exhibits low overpotential and high stability, surpassing commercial Pt/C catalysts at higher current densities. 5. **Broader Impact**: The study provides new insights into the synthesis and design of efficient electrocatalysts, potentially reducing the cost and increasing the availability of hydrogen production technologies.