Earth-Abundant Electrocatalysts for Water Splitting: Current and Future Directions

Abstract

Of all the available resources given to mankind, the sunlight is perhaps the most abundant renewable energy resource, providing more than enough energy on earth to satisfy all the needs of humanity for several hundred years. Therefore, it is transient and sporadic that poses issues with how the energy can be harvested and processed when the sun does not shine. Scientists assume that electro/photoelectrochemical devices used for water splitting into hydrogen and oxygen may have one solution to solve this hindrance. Water electrolysis-generated hydrogen is an optimal energy carrier to store these forms of energy on scalable levels because the energy density is high, and no air pollution or toxic gas is released into the environment after combustion. However, in order to adopt these devices for readily use, they have to be low-cost for manufacturing and operation. It is thus crucial to develop electrocatalysts for water splitting based on low-cost and land-rich elements. In this review, I will summarize current advances in the synthesis of low-cost earth-abundant electrocatalysts for overall water splitting, with a particular focus on how to be linked with photoelectrocatalytic water splitting devices. The major obstacles that persist in designing these devices. The potential future developments in the production of efficient electrocatalysts for water electrolysis are also described.

Single‐Step Solid‐State Scalable Transformation of Ni‐Based Substrates to High‐Oxidation State Nickel Sulfide Nanoplate Arrays as Exceptional Bifunctional Electrocatalyst for Overall Water Splitting

“…Finally, the ESCA was calculated using the formula, ECSA = C C s dl cm 2 ESCA ; where, C s is the specific capacitance of flat surface in alkaline medium (40 µF cm −2 ). [33] Based on the above calculation, the highest ECSA value of 40 cm 2 ESCA was observed for NIS-450. The ECSA normalized OER and HER activity of NIS-450 is shown in Figure S8, Supporting Information.…”

“…The synthesis process developed in this work is highly economic and scalable to industrial scales. The process was scaled-up, and a 40 cm 2 Ni foil was successfully transformed to NIS with high uniformity in the entire area (Figure 1g). The cross-sectional SEM analysis at five different points in the scaled-up NIS-450 substrate has similar plate-like structures, confirming the ease of scalability for the process developed in this study (Figure 1h-l).…”

“…[ 1 ] Electrocatalytic water splitting has evolved as a major research area, because of its potential as a feasible and sustainable source of continuous hydrogen production. [ 2 ] However, the high overpotentials for the sluggish hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) inhibit the practical applicability of the process. [ 3 ] Pt for HER, and IrO 2 or RuO 2 for OER, are considered the benchmarking electrocatalysts.…”

Hydrogen as a Clean and Sustainable Energy Vector for Global Transition from Fossil-Based to Zero-Carbon

“…Indeed, the water electrolysis process principle relies on the use of electricity to split the pure water into hydrogen and oxygen. Water is an abundant resource on Earth and different types of power sources can be used for the process [17,18]. However, to assess the profits and the economic feasibility of employing water electrolysis, the cost, the efficiency, and the carbon emissions of the used power source for electricity generation must be considered [19].…”

Catalytic Hydrogen Production, Storage and Application

“…The photocatalytic hydrogen production technique is also gaining researchers' attention as it is environmentally friendly. A research paper in this Special Issue [7] presents the fabrication of Ni complexes and their application to photocatalytic hydrogen evolution. The research in this paper proved that the mechanisms for photocatalysis and electrocatalysis follow different pathways using the same catalysts.…”