Fe-N-C catalysts, as promising non-precious metal alternatives for the oxygen reduction reaction (ORR), still suffer from severe mass transport limitations in proton exchange membrane fuel cells (PEMFCs) due to water flooding of active sites embedded in micropores. Although pore engineering through a selected template is a general strategy, the structural features of an ideal template, particularly those governing the exposure of active sites and thus affecting mass transport, remain elusive. Here, we demonstrate that low-porosity carbon templates maximize the ratio of active sites distributed at or near the surface, thereby enhancing their exposure and accessibility while reducing mass transport resistance during the ORR process. The C_lp-1@PPy and C_lp-2@PPy (PPy = polypyrrole) catalysts, derived from low-porosity carbon templates, achieve peak power densities of 0.96 and 1.03 W·cm⁻² under H₂/O₂ and 0.50 and 0.52 W·cm⁻² under H₂/air, demonstrating excellent performance in PEMFC tests. Structural and electrochemical characterizations reveal that the enhanced surface exposure of active sites effectively mitigates mass transport resistance during the ORR, thereby offering a general design principle for overcoming mass transport limitations in Fe-N-C catalysts for PEMFC applications.

Chlorine (Cl₂) is one of the most important chemicals produced by the electrolysis of brine solutions and is a key raw material for many areas of industrial chemistry. For nearly half a century, dimensionally stable anode (DSA) made from a mixture of RuO₂ and TiO₂ solid oxides coated on Ti substrate has been the most widely used electrode for chlorine evolution reaction (CER). In harsh operating environments, the stability of DSAs remains a major challenge greatly affecting their lifetime. The deactivation of DSAs significantly increases the cost of the chlor-alkali industry due to the corrosion of Ru and the formation of the passivation layer TiO₂. Therefore, it is urgent to develop catalysts with higher activity and stability, which requires a thorough understanding of the deactivation mechanism of DSA catalysts. This paper reviews existing references on the deactivation mechanisms of DSA catalysts, including both experimental and theoretical studies. Studies on how CER selectivity affects electrode stability are also discussed. Furthermore, studies on the effects of the preparation process, elemental composition, and surface/interface structures on the DSA stability and corresponding improvement strategies are summarized. The development of other non-DSA-type catalysts with comparable stability is also reviewed, and future opportunities in this exciting field are also outlined.

Electrolytic water splitting by renewable energy is a technology with great potential for producing hydrogen (H₂) without carbon emission, but this technical route is hindered by its huge energy (electricity) cost, which is mainly wasted by the anode oxygen evolution reaction (OER) while the value of the anode product (oxygen) is very limited. Replacing the high-energy-cost OER with a selective organic compound electrooxidation carried out at a relatively lower potential can reduce the electricity cost while producing value-added chemicals. Currently, H₂ generation coupled with synthesis of value-added organic compounds faces the challenge of low selectivity and slow generation rate of the anodic products. One-dimensional (1D) nanocatalysts with a unique morphology, well-defined active sites, and good electron conductivity have shown excellent performance in many electrocatalytic reactions. The rational design and regulation of 1D nanocatalysts through surface engineering can optimize the adsorption energy of intermediate molecules and improve the selectivity of organic electrooxidation reactions. Herein, we summarized the recent research progress of 1D nanocatalysts applied in different organic electrooxidation reactions and introduced several different fabrication strategies for surface engineering of 1D nanocatalysts. Then, we focused on the relationship between surface engineering and the selectivity of organic electrooxidation reaction products. Finally, future challenges and development prospects of 1D nanocatalysts in the coupled system consisting of organic electrooxidation and hydrogen evolution reactions are briefly outlined.