Rational Design Strategies for Carbon Nanotube-Based Non-Precious Metal HER Catalysts: A Review

Abstract

Developing efficient and cost-effective electrocatalysts for the hydrogen evolution reaction (HER) remains a central challenge for sustainable hydrogen production, as replacing platinum with non-precious metals is often hindered by limitations in intrinsic activity and structural stability. Carbon nanotubes (CNTs) have emerged as an enabling platform that extends far beyond their conventional role as conductive supports, offering opportunities for precise control over electron transport pathways, stabilization of active species, nanoscale confinement, and tailored surface functionalization. This review adopts a material design perspective rather than an element-based classification, and critically examines advanced strategies for constructing active HER sites on CNT frameworks, including single-atom engineering, well-defined heterointerface formation, multi-metallic cooperative effects, and defector strain-induced electronic modulation. Recent developments in CNT-based macroarchitectures aimed at improving long-term electrode robustness are also discussed. By correlating structural features with catalytic performance across these strategies, this work identifies key design principles for achieving high activity and durability in CNT-based HER electrocatalysts, and outlines future research directions involving precise synthesis control, operando mechanistic studies, and emerging concepts such as high-entropy catalytic systems.