Increasing demand for finding eco-friendly and everlasting energy sources is now totally depending on fuel cell technology. Though it is an eco-friendly way of producing energy for the urgent requirements, it needs to be improved to make it cheaper and more eco-friendly. Although there are several types of fuel cells, the hydrogen (H2) and oxygen (O2) fuel cell is the one with zero carbon emission and water as the only byproduct. However, supplying fuels in the purest form (at least the H2) is essential to ensure higher life cycles and less decay in cell efficiency. The current large-scale H2 production is largely dependent on steam reforming of fossil fuels, which generates CO2 along with H2 and the source of which is going to be depleted. As an alternate, electrolysis of water has been given greater attention than the steam reforming. The reasons are as follows: the very high purity of the H2 produced, the abundant source, no need for high-temperature, high-pressure reactors, and so on. In earlier days, noble metals such as Pt (cathode) and Ir and Ru (anode) were used for this purpose. However, there are problems in employing these metals, as they are noble and expensive. In this review, we elaborate how the group VIII 3d metal sulfide, selenide, and phosphide nanomaterials have arisen as abundant and cheaper electrode materials (catalysts) beyond the oxides and hydroxides of the same. We also highlight the evaluation perspective of such electrocatalysts toward water electrolysis in detail.

To avoid unnoticed errors made by researchers who are working in the area of nanostructured materials for water splitting, the correct and precise use of evaluation parameters is discussed in detail, stating their acceptability and validity.

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until at least we can breach the thermoneutral overpotential (1.481 V) barrier.

Scheme 1. Graphical Sketch Advocating against the Use of Dynamic LSV/CV Responses for Deriving Tafel Plots a a TS and j 0 denote Tafel slope and exchange current density, respectively.

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Transition metal hydroxides (M‐OH) and their heterostructures (X|M‐OH, where X can be a metal, metal oxide, metal chalcogenide, metal phosphide, etc.) have recently emerged as highly active electrocatalysts for hydrogen evolution reaction (HER) of alkaline water electrolysis. Lattice hydroxide anions in metal hydroxides are primarily responsible for observing such an enhanced HER activity in alkali that facilitate water dissociation and assist the first step, the hydrogen adsorption. Unfortunately, their poor electronic conductivity had been an issue of concern that significantly lowered its activity. Interesting advancements were made when heterostructured hydroxide materials with a metallic and or a semiconducting phase were found to overcome this pitfall. However, in the midst of recently evolving metal chalcogenide and phosphide based HER catalysts, significant developments made in the field of metal hydroxides and their heterostructures catalysed alkaline HER and their superiority have unfortunately been given negligible attention. This review, unlike others, begins with the question of why alkaline HER is difficult and will take the reader through evaluation perspectives, trends in metals hydroxides and their heterostructures catalysed HER, an understanding of how alkaline HER works on different interfaces, what must be the research directions of this field in near future, and eventually summarizes why metal hydroxides and their heterostructures are inevitable for energy‐efficient alkaline HER.