The electrode remains the quintessential interface where chemical, electrical, and mechanical phenomena converge. Over the past three years, the field has shifted from incremental porosity tuning toward a holistic design philosophy that treats the electrode as a dynamic, multi-scale system. This review highlights recent breakthroughs in atomic-scale active-site engineering, gradient and 3D architectures, and adaptive interfaces, with a focus on how these advances are reshaping batteries, electrolyzers, and neural interfaces.

1. Atomic-scale design: Beyond single-atom catalysts

Single-atom catalysts (SACs) have dominated the literature, but their practical deployment has been hindered by low metal loading and migration under operating conditions. A pivotal advance in 2024 came from the group of Zhang et al. (Nature Catalysis, 2024, 7, 412–423), who demonstrated a "coordination-unsaturated" Ni–N₃ motif embedded in a nitrogen-doped carbon matrix. By deliberately removing one axial nitrogen ligand, they increased the d-band center relative to the Fermi level, boosting the oxygen reduction reaction (ORR) activity by 3.2-fold over conventional Ni–N₄ sites. More importantly, they achieved a metal loading of 8.5 wt% without aggregation by using a zinc-assisted volatilization strategy during pyrolysis—a critical step toward industrial relevance.

In parallel, the concept of "dual-atom" or "diatomic" sites has matured. Li et al. (Advanced Materials, 2025, 37, 2408812) reported a heteronuclear Fe–Co diatomic site bridged by a sulfur atom (Fe–S–Co) on a porous carbon support. The asymmetric electron distribution between Fe and Co creates a localized electric field that lowers the activation energy for CO₂ reduction to CO, achieving a Faradaic efficiency of 98.6% at −0.4 V vs. RHE. This work underscores that precise control of the bridging atom, not just the metal pair, dictates selectivity.

2. Gradient and 3D architectures: Managing mass transport and stress

While atomic design optimizes intrinsic activity, macroscopic electrode architecture governs transport and durability. A major breakthrough in thick electrodes came from the "gradient porosity" approach. Wang and co-workers (Energy & Environmental Science, 2025, 18, 1567–1580) fabricated a lithium-ion battery cathode with a pore-size gradient from 200 nm at the current collector to 2 µm at the electrolyte interface. Using operando synchrotron X-ray tomography, they showed that this gradient reduces electrolyte concentration polarization by 47% at 5C discharge, enabling a thick electrode (4 mAh/cm²) to retain 91% capacity after 500 cycles—a performance previously unattainable.

For silicon anodes, mechanical fracture remains the Achilles' heel. A striking solution emerged from "yolk–shell" engineering with internal void space, but the field has now moved towardself-healingbinders. The 2025 work by Chen et al. (ACS Nano, 2025, 19, 11230–11242) introduced a dynamic covalent network based on boronic ester bonds. When the silicon particle expands during lithiation, the binder's bonds break and reform, dissipating stress without losing electronic percolation. This electrode sustained 2,100 cycles at 1 A/g with 88% capacity retention—a benchmark for alloying anodes.

3. Adaptive and bio-inspired interfaces: The next frontier

Perhaps the most exciting direction is the design of electrodes that respond to their environment. In the realm of neural interfaces, rigid electrodes cause gliosis and signal degradation. A landmark study by Park et al. (Science Advances, 2025, 11, eadr8956) reported a "morphing" electrode made of a shape-memory polymer substrate coated with a conductive PEDOT:PSS/gold nanowire mesh. Upon implantation, the electrode transitions from a stiff needle (for insertion) to a soft, conformal film (modulus ~1 MPa) within 30 seconds at body temperature. This reduced microglial activation by 80% compared to conventional platinum electrodes, and single-unit recordings remained stable for 12 months in non-human primates.

In electrocatalysis, bio-inspired "gas-breathing" electrodes have emerged for CO₂ reduction. Inspired by alveoli, researchers at MIT (Keller et al.,Joule, 2025, 9, 101234) designed a hierarchical electrode with hydrophobic microchannels that deliver CO₂ directly to the catalyst–electrolyte triple phase boundary. By decoupling gas transport from ion transport, they achieved a partial current density of 1.2 A/cm² for CO production with an energy efficiency of 52%—a record for a membrane electrode assembly. The key was a fluorinated carbon layer that prevents electrolyte flooding, a persistent failure mode in gas diffusion electrodes.

4. Computational-driven design: Inverse engineering

The proliferation of machine learning (ML) has transformed electrode design from trial-and-error to inverse optimization. In 2025, a collaborative effort between Toyota Research Institute and Stanford (Kim et al.,Nature Computational Science, 2025, 5, 388–399) used a graph neural network to predict the optimal pore network for a given redox flow battery electrolyte. The model, trained on 12,000 synthetic electrode geometries, generated a "bifurcated channel" design that improved pump efficiency by 33% while maintaining mass transfer. This design was directly 3D-printed into carbon electrodes, validating the simulation-to-fabrication pipeline.

5. Future outlook and grand challenges

Despite these advances, several bottlenecks remain. First,operandocharacterization at the atomic scale under realistic current densities is still limited; most SAC studies rely on ex-situ X-ray absorption spectroscopy. Second, the scalability of bio-inspired designs—such as the morphing electrode—requires manufacturing processes that are compatible with cleanroom or roll-to-roll fabrication. Third, the trade-off between active site density and ionic conductivity in thick electrodes persists; gradient designs help but do not fully resolve the ion transport limitation at extreme fast charging (10C+).

Looking forward, I foresee three converging trends: (i)self-regulated electrodesthat adjust their porosity or surface charge in response to state-of-charge via stimuli-responsive polymers; (ii)multi-functional interphasesthat simultaneously conduct ions, electrons, and heat, eliminating the need for separate additives; and (iii)closed-loop digital twinswhere real-time sensor data from the electrode is fed back into an ML model to adjust operating parameters—essentially making the electrode part of a cyber-physical system.

The next decade will likely witness the emergence of electrodes designed not as passive scaffolds but as active, adaptive components that blur the line between material and machine. The progress from atomic-scale motifs to system-level architectures is no longer linear but deeply integrated, and the field is only beginning to exploit the full design space.

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