Honglin Gao

As a key clean energy technology, water electrolysis relies on advances in electrocatalysts. Thus, the pursuit of high-performance, durable, and inexpensive catalysts defines a pivotal research frontier. In this work, Se _x -Al ₁ Cr ₂ /NF catalysts were fabricated via a one-step hydrothermal method. Moderate Se doping induces the surface reconstruction of the Ni foam substrate into a nickel diselenide (NiSe ₂ ) phase, substantially boosting OER performance. The optimal Se _0.8 -Al ₁ Cr ₂ /NF shows remarkable performance in alkaline electrolytes, achieving an overpotential of 352.7 mV at 100 mA cm ⁻² and a Tafel slope of 30.5 mV dec ⁻¹ . At the end of a 100-hour continuous run, its overpotential exhibits an increase of 10 mV, demonstrating excellent long-term stability. This work presents a viable approach to developing high-performance OER electrocatalysts for sustainable energy conversion applications.

Water electrolysis stands out as a practical way to produce hydrogen and tackle both energy shortages and pollution. However, the oxygen evolution reaction (OER) is slow and demands a lot of extra energy because of high overpotential. Therefore, finding affordable and efficient OER electrocatalysts is important and urgent. Layered double hydroxides (LDHs) have caught researchers’ attention as solid alkaline OER candidates. However, their poor conductivity and lack of active sites keep them from reaching their full potential. Non-metallic S-doping has emerged as an effective modification strategy. We conducted independent experimental research on three S-doped LDHs (MnCo, NiCo, AlCr) via a one-step hydrothermal method and performed comparative electrochemical tests. The results show that the metal composition of LDHs exerts a significant modulating effect on the modification efficacy of sulfur doping. Among the three samples, S-MnCo LDH delivers the optimal performance, with overpotentials as low as 173 mV and 217 mV at current densities of 50 mA cm ⁻² and 100 mA cm ⁻² , and its overall activity outperforms commercial RuO ₂ . Our findings offer useful direction for designing smarter catalysts in the future.

The oxygen evolution reaction (OER) is a key kinetic bottleneck in water electrolysis because it involves multistep proton-coupled electron transfer, the evolution of oxygen-containing intermediates and O–O bond formation. MXenes, as two-dimensional transition-metal carbides, nitrides and carbonitrides, possess high electrical conductivity, hydrophilic surfaces, tunable surface terminations and adjustable layered structures, making them promising platforms for OER catalyst design. However, their limited intrinsic active sites, sheet restacking and oxidative instability under anodic conditions restrict their direct application. This review firstly discusses the fundamental OER pathways based on the adsorbate evolution mechanism (AEM), lattice oxygen mechanism (LOM) and oxide path mechanism (OPM), providing a mechanistic basis for understanding intermediate adsorption, oxygen activation and working-state evolution. Then, a system framework from low-dimensional and micro-level control to high-dimensional and macro-level integration is constructed. The framework covers four levels: atom and local structure, interface, morphology and composite electrode. Drawing on specific examples, this review analyzes the characteristics and mechanisms of modification strategies from four different perspectives, starting with the basic principles of modification. These strategies include micro-scale, low-dimensional approaches such as “Vacancy and other atomic-Level Regulation”, macro-scale, high-dimensional methods like “Composite Engineering”, as well as intermediate approaches involving “Interface engineering” and “morphology engineering”. Special emphasis is placed on distinguishing between beneficial surface reconstruction of catalytically active hydroxyl oxide species and destructive oxidation. Finally, the review identified the unresolved key challenges, including the fuzziness of active sites, the diversity of initial material states and the lack of stability under industrial conditions, and looked forward to the future direction of reasonable design, operational characterization and device-level evaluation. Through this cross-scale analysis, this review aims to clarify the relationship between structure–activity–stability, and provide practical guidance for designing efficient, durable and experimentally verifiable MXene-based OER electrodes.

Electrochemical CO₂ reduction reaction (CO₂RR) is a key technology for achieving carbon neutrality and efficient utilization of renewable energy, capable of converting CO₂ into high-value-added carbon-based fuels and chemicals. Copper (Cu)-based catalysts have attracted significant attention due to their unique performance in generating multi-carbon (C₂₊) products such as ethylene and ethanol; however, there are still many controversies regarding their complex reaction mechanisms, active sites, and the dynamic evolution of intermediates. In situ Raman spectroscopy, with its high surface sensitivity, applicability in aqueous environments, and precise detection of molecular vibration modes, has become a powerful tool for studying the structural evolution of Cu catalysts and key reaction intermediates during CO₂RR. This article reviews the principles of electrochemical in situ Raman spectroscopy and its latest developments in the study of CO₂RR on Cu-based catalysts, focusing on its applications in monitoring the dynamic structural changes of the catalyst surface (such as Cu⁺, Cu⁰, and Cu²⁺ oxide species) and identifying key reaction intermediates (such as *CO, *OCCO(*O=C-C=O), *COOH, etc.). Numerous studies have shown that Cu-based oxide precursors undergo rapid reduction and surface reconstruction under CO₂RR conditions, resulting in metallic Cu nanoclusters with unique crystal facets and particle size distributions. These oxide-derived active sites are considered crucial for achieving high selectivity toward C₂₊ products. Time-resolved Raman spectroscopy and surface-enhanced Raman scattering (SERS) techniques have further revealed the dynamic characteristics of local pH changes at the electrode/electrolyte interface and the adsorption behavior of intermediates, providing molecular-level insights into the mechanisms of selectivity control in CO₂RR. However, technical challenges such as weak signal intensity, laser-induced damage, and background fluorescence interference, and opportunities such as coupling high-precision confocal Raman technology with in situ X-ray absorption spectroscopy or synchrotron radiation Fourier transform infrared spectroscopy in researching the mechanisms of CO₂RR are also put forward.