Machine Learning‑Assisted Low‑Dimensional Electrocatalysts Design for Hydrogen Evolution Reaction

Efficient electrocatalysts are crucial for hydrogen generation from electrolyzing water. Nevertheless, the conventional trial and error method for producing advanced electrocatalysts is not only cost-ineffective but also time-consuming and labor-intensive. Fortunately, the advancement of machine learning brings new opportunities for electrocatalysts discovery and design. By analyzing experimental and theoretical data, machine learning can effectively predict their hydrogen evolution reaction (HER) performance. This review summarizes recent developments in machine learning for low-dimensional electrocatalysts, including zero-dimension nanoparticles and nanoclusters, one-dimensional nanotubes and nanowires, two-dimensional nanosheets, as well as other electrocatalysts. In particular, the effects of descriptors and algorithms on screening low-dimensional electrocatalysts and investigating their HER performance are highlighted. Finally, the future directions and perspectives for machine learning in electrocatalysis are discussed, emphasizing the potential for machine learning to accelerate electrocatalyst discovery, optimize their performance, and provide new insights into electrocatalytic mechanisms. Overall, this work offers an in-depth understanding of the current state of machine learning in electrocatalysis and its potential for future research

Template-Engaged Synthesis of 1D Hierarchical Chainlike LiCoO₂ Cathode Materials with Enhanced High-Voltage Lithium Storage Capabilities

A novel 1D hierarchical chainlike LiCoO₂ organized by flake-shaped primary particles is synthesized via a facile template-engaged strategy by using CoC₂O₄·2H₂O as a self-sacrificial template obtained from a simple coprecipitation method. The resultant LiCoO₂ has a well-built hierarchical structure, consisting of secondary micrometer-sized chains and sub-micrometer-sized primary flakes, while these primary LiCoO₂ flakes have specifically exposed fast-Li⁺-diffused active {010} facets. Owing to this unique hierarchical structure, the chainlike LiCoO₂ serves as a stable cathode material for lithium-ion batteries (LIBs) operated at a high cutoff voltage up to 4.5 V, enabling highly reversible capacity, remarkable rate performance, and long-term cycle life. Specifically, the chainlike LiCoO₂ can deliver a reversible discharge capacity as high as 168, 156, 150, and 120 mAh g^–1 under the current density of 0.1, 0.5, 1, and 5 C, respectively, while about 85% retention of the initial capacity can be retained after 200 cycles under 1 C at room temperature. Moreover, the chainlike LiCoO₂ also shows an excellent cycling stability at a wide operating temperature range, showing the capacity retention of ∼73% after 200 cycles at 55 °C and of ∼68% after 50 cycles at −10 °C, respectively. The work described here suggests the great potential of the hierarchical chainlike LiCoO₂ as high-voltage cathode materials aimed toward developing advanced LIBs with high energy density and power density

V3S4 Nanosheets Anchored on N, S Co-Doped Graphene with Pseudocapacitive Effect for Fast and Durable Lithium Storage

Construction of a suitable hybrid structure has been considered an important approach to address the defects of metal sulfide anode materials. V3S4 nanosheets anchored on an N, S co-coped graphene (VS/NSG) aerogel were successfully fabricated by an efficient self-assembled strategy. During the heat treatment process, decomposition, sulfuration and N, S co-doping occurred. This hybrid structure was not only endowed with an enhanced capability to buffer the volume expansion, but also improved electron conductivity as a result of the conductive network that had been constructed. The dominating pseudocapacitive contribution (57.78% at 1 mV s−1) enhanced the electrochemical performance effectively. When serving as anode material for lithium ion batteries, VS/NSG exhibits excellent lithium storage properties, including high rate capacity (480 and 330 mAh g−1 at 5 and 10 A g−1, respectively) and stable cyclic performance (692 mAh g−1 after 400 cycles at 2 A g−1)

Flakelike LiCoO₂ with Exposed {010} Facets As a Stable Cathode Material for Highly Reversible Lithium Storage

A thick and dense flakelike LiCoO₂ with exposed {010} active facets is synthesized using Co­(OH)₂ nanoflake as a self-sacrificial template obtained from a simple coprecipitation method, and served as a cathode material for lithium ion batteries. When operated at a high cutoff voltage up to 4.5 V, the resultant LiCoO₂ exhibits an outstanding rate capability, delivering a reversible discharge capacity as high as 179, 176, 168, 116, and 96 mA h g^–1 at 25 °C under the current rate of 0.1, 0.5, 1, 5, and 10 <i>C</i>, respectively. When charge/discharge cycling at 55 °C, a high specific capacity of 148 mA h g^–1 (∼88% retention) can be retained after 100 cycles under 1 C, demonstrating excellent cycling and thermal stability. Besides, the flakelike LiCoO₂ also shows an impressive low-temperature electrochemical activity with specific capacities of 175 (0.1 C) and 154 mA h g^–1 (1 <i>C</i>) at −10 °C, being the highest ever reported for a subzero-temperature lithium storage capability, as well as 52% capacity retention even after 80 cycles under 1 <i>C</i>. Such superior high-voltage electrochemical performances of the flakelike LiCoO₂ operated at a wide temperature range are mainly attributed to its unique hierarchical structure with specifically exposed facets. The exposed {010} active facets provide a preferential crystallographic orientation for Li-ion migration, while the micrometer-sized secondary particles agglomerated by submicron primary LiCoO₂ flakes endow the electrode with better structural integrity, both of which ensure the LiCoO₂ cathode to manifest remarkably enhanced reversible lithium storage properties

Realizing Ultrafast and Robust Sodium-Ion Storage of Iron Sulfide Enabled by Heteroatomic Doping and Regulable Interface Engineering

Fe-based sulfides are a promising type of anode material for sodium-ion batteries (SIBs) due to their high theoretical capacities and affordability. However, these materials often suffer from issues such as capacity deterioration and poor conductivity during practical application. To address these challenges, an N-doped Fe7S8 anode with an N, S co-doped porous carbon framework (PPF-800) was synthesized using a template-assisted method. When serving as an anode for SIBs, it delivers a robust and ultrafast sodium storage performance, with a discharge capacity of 489 mAh g−1 after 500 cycles at 5 A g−1 and 371 mAh g−1 after 1000 cycles at 30 A g−1 in the ether-based electrolyte. This impressive performance is attributed to the combined influence of heteroatomic doping and adjustable interface engineering. The N, S co-doped carbon framework embedded with Fe7S8 nanoparticles effectively addresses the issues of volumetric expansion, reduces the impact of sodium polysulfides, improves intrinsic conductivity, and stimulates the dominant pseudocapacitive contribution (90.3% at 2 mV s−1). Moreover, the formation of a stable solid electrolyte interface (SEI) film by the effect of uniform pore structure in ether-based electrolyte produces a lower transfer resistance during the charge–discharge process, thereby boosting the rate performance of the electrode material. This work expands a facile strategy to optimize the electrochemical performance of other metal sulfides