• Carbon-based electrocatalysts show promise for water splitting but face distinct challenges at high current densities, including bubble effects and stability issues.
• The review highlights the need for testing catalysts under industrial-relevant high current densities, not just low laboratory conditions.
• Strategies such as defect engineering, heteroatom doping, and metal modification are discussed to enhance performance at high current densities.
• Decoupling HER and OER processes is proposed as a promising approach to overcome high-current-density limitations.