Hydrogen

Hydrogen (H) — 10-Year Trends

As of 2026-09-11 · the last 10 years

Research intensity has held steady at about 82% of the element's own all-time peak, a level maintained since the window opened in 2016.

Research intensity ran from about 85% of the element's own all-time peak in 2016 to about 82% in 2026 — essentially flat across the window, and the all-time peak (1980) lies before this window. Over the same span its share of research attention across all elements held steady. Among the 118 elements, hydrogen has one of the largest research literatures of any element.

The number of papers involving the element rose from about 158,322 in 2016 to about 396,442 in 2025 (2.5x). That matches the growth of the literature as a whole over the same years: the general tide of scientific output, not a surge specific to the element.

The largest research community is Hydrogen Production, Storage, and Fuel Cell Technologies, where hydrogen is central to the work, appearing in about 47% of the community's papers. This group accounts for about 37% of hydrogen’s recent research, a share that has risen from 29% in the previous period. The work focuses on the practical challenges of the energy transition, with distinctive emphasis on liquid hydrogen, PEM fuel cells, and hydrogen refueling infrastructure. A 2018 paper on the role of hydrogen and fuel cells in the global energy system, cited over 3,900 times, remains a foundational text, while a 2025 review in Nature Energy on the green hydrogen implementation gap, cited over 440 times, reflects the current focus on deployment realities.

A second major area is Electrocatalytic Nitrate Reduction and Ammonia Synthesis, where hydrogen is also central, involved in about 40% of the papers. This community represents about 15% of hydrogen’s recent research and has held steady, growing slightly from 10.5% in the earlier period. The research centers on electrochemical ammonia synthesis and nitrate electroreduction, aiming to produce ammonia sustainably. A 2021 study in Nature Communications on electrochemical ammonia synthesis via nitrate reduction on iron single-atom catalysts, cited over 1,500 times, anchors this field, alongside a 2023 Nature Catalysis paper on ultralow overpotential nitrate reduction, cited over 940 times.

The third material community is Transition Metal Electrocatalysts for Alkaline Hydrogen Evolution, a subcommunity within the broader field of water splitting. Here, hydrogen is one strand of a broader community, appearing in about 20% of its papers. This group’s share of hydrogen’s research has declined from 25.5% to about 14% over the window. The work involves designing transition metal catalysts to enhance the efficiency of the hydrogen evolution reaction in alkaline media. The most cited paper in the entire window belongs to this community: a 2017 Science paper combining theory and experiment in electrocatalysis, cited over 12,000 times. More recently, a 2024 Chemical Reviews paper on bifunctional electrocatalysts for overall water splitting, cited over 780 times, highlights ongoing efforts to improve catalyst performance.

Overall, the composition of hydrogen research has shifted toward practical energy applications and ammonia synthesis, while the share of work focused specifically on alkaline hydrogen evolution catalysts has decreased. The remaining 35% of research is distributed across other smaller communities.

For a deeper look at the current state of hydrogen research, see the Last 12 Months and Executive Brief reports.