Catalyst substances that grew significantly in recent years are presented in the Figure alongside their growth trends. Co-Fe alloy, Fe-Ni alloy, vanadium, niobium, zinc, nickel selenide, cobalt diselenide, nickel sulfide, MoO2, and MoO3 are identified as the emerging catalysts. Co-Fe alloy and Fe-Ni alloy are efficient bifunctional catalysts capable of performing both oxygen evolution (OER) and oxygen reduction (ORR) used in applications such as zinc-air batteries and water splitting. Nickel selenides are efficient for hydrogen evolution due to their low overpotential. Cobalt diselenide is an efficient non-noble metal based bifunctional catalyst capable of performing both oxygen evolution and hydrogen evolution (HER), used mostly in HER studies. Composites containing various nickel sulfides are bifunctional catalysts capable of performing both OER and HER reactions with low overpotentials. The growth of molybdenum dioxide in recent years is due to its low cost, high stability, and low overpotential for HER applications. Due to its stability in alkaline medium and efficient HER catalytic performance, there is increase in research interest in molybdenum trioxide recently. To develop a broader perspective of the substances used as electrocatalysts and to find use of substances with varying composition such as layered double hydroxides (LDH) and MXenes, we delved into the prevalent substance classes and their patent to journal ratios (Figure ). LDH, transition metals, transition metal phosphides, and noble metals are among the top substances used as catalysts. Due to its high surface area, tunable and variable composition, stability, and ease of doping and intercalation, LDH and composites containing LDH are studied for HER, OER, and ORR, which are applied in fuel cells, overall water splitting, and zinc-air batteries. Other carbon-based substances, and polymers in the list are used as supports, binders, and fillers. MXene is another substance class like LDH, that did not appear in the top catalyst substances due to its variable composition. MXenes are layered substances which possess multiple sites known for their catalytic activity such as metal nitride, metal carbide, and carbon nitride within their structure. These favorable properties have driven studies using MXenes as catalysts and co-catalysts for water splitting reactions. The figure also presents the patent to journal ratio, which is high among the metallic catalysts compared to the other catalysts. We then delved into reaction related topics and their patent to journal ratio (Figure ). The publication volumes of the top 25 reaction topics show oxygen evolution reaction (OER), electrochemical reduction, hydrogen evolution reaction (HER), and water splitting as the top reaction types. OER is a well-known half reaction in the overall water splitting process used to produce hydrogen. OER also plays a significant role in zinc-air batteries; these batteries hold a higher energy density than lithium batteries, hence their emergence as an alternative for applications requiring less voltage. Due to the efforts to generate hydrogen, a potential green fuel, hydrogen evolution reaction has gained significance. Platinum is considered as the best HER catalyst; any breakthrough in finding sustainable alternative to Pt will have significant impact in the green hydrogen production industry. The co-occurrence between catalysts and reactions is shown in Figure . One of the observations is the use of layered materials such as graphene, graphite, sulfur, and molybdenum sulfide in intercalation reactions. Molybdenum sulfide, cobalt, copper, molybdenum, nickel phosphide, and molybdenum carbide also co-occur with the hydrogen evolution reaction. The most indexed uses and their patent to journal ratio are presented in Figure . As seen in the indexed reactions, uses related to water splitting are present in most publications. A notable usage is the bifunctional catalysts, which are capable of catalyzing both the anode and cathode reactions in overall water splitting, and zinc-air battery. A variety of transition metal based sulfide, phosphide, 60 oxide, and alloy 62 catalysts have displayed bifunctional capabilities. Lastly, reduction reaction catalysts have the highest patent to journal ratio among of the various uses, which seems to be due to the high commercial interest in oxygen reduction reaction catalysts having applications in fuel cells. An analysis of cooccurrence of the usage and catalyst substances (Figure ), shows that carbon, graphite, graphene, and nitrogen are the primary non-metal substances that co-occurred with catalysts/catalysis-based usage concepts; nickel, cobalt, iron, copper, molybdenum disulfide, and zinc are the metal substances that reveal high to moderate co-occurrence in electrocatalyst-related research documents. The most prevalent devices or parts of the devices indexed from non-noble metal electrocatalyst related publications are fuel cells and batteries (Figure ). Hydrogen based fuel cells play a major role in the proposed hydrogen economy, and research on fuel cells is driven by the need for efficient, stable, and cost effective catalysts for ORR and hydrogen oxidation reactions. Batteries have become essential for storing the various forms of green energy, solving the issue that arises due to their intermittent nature. However, the primary driver behind the need for nonnoble metal alternatives in battery research are the zinc-air batteries. Zinc-air batteries involve ORR and OER which traditionally need expensive platinum catalysts, hence need alternatives. Solar cells, supercapacitors, and photoelectrochemical cells are other popular devices. To bring down the cost of solar cells, there is a need for alternatives to the platinum counter electrodes. Figure shows the prevalence of the catalyst substances within different apparatus types. Zinc and ruthenium dioxide have high co-occurrence with batteries due to the battery technologies such as zinc-air and zinc-ion, where ruthenium dioxide is used as oxygen evolution reaction catalyst. Palladium is widely used as catalyst in fuel cell related applications. Owing to their photocatalytic activity, titania is prevalent in the solar cells and photoanodes. Photoanodes are part of photoelectrochemical cells for overall water splitting, where ferric oxide is used as the photocatalyst, and NiO, 71 cobalt phosphide, and nickel dihydroxide are used as cocatalysts for oxygen evolution reaction.