The proton exchange membrane water electrolyzer (PEM-WE) is a well-known green technology for hydrogen production. The main obstacle to its development, on a large scale, is the sluggish kinetics of the oxygen evolution reaction (OER). At present, the design of acid-stable electrocatalysts with low overpotential and excellent stability for the OER constitutes an important activity in electrocatalysis. This review presents an analysis of the fundamentals and strategies for the design of advanced electrocatalysts for oxygen evolution, reaction mechanisms, and OER descriptors. The scrutiny of OER electrocatalysts, with elemental composition from single- to multielemental, are presented. In addition, the purpose of high-entropy alloys (HEAs), a recent research strategy, for the design of advanced materials is summarized. Briefly, the effect of support materials, which are beneficial for modulating the electronic properties of catalysts, is presented. Finally, the prospects for the development of acidic OER electrocatalysts are given.

Zero-export photovoltaic systems are an option to transition to Smart Grids. They decarbonize the sector without affecting third parties. This paper proposes the analysis of a zero-export PVS with a green hydrogen generation and storage system. This configuration is feasible to apply by any self-generation entity; it allows the user to increase their resilience and independence from the electrical network. The technical issue is simplified because the grid supplies no power. The main challenge is finding an economic balance between the savings in electricity billing, proportional to the local electricity rate, and the complete system's investment, operation, and maintenance expenses. This manuscript presents the effects of the power sizing on the efficacy of economic savings in billing (${\eta }_{Saving}$) and the effects of the cost reduction on the levelized cost of energy (LCOE) and a discounted payback period (DPP) based on net present value. In addition, this study established an analytical relationship between LCOE and DPP. The designed methodology proposes to size and selects systems to use and store green hydrogen from the zero-export photovoltaic system. The input data in the case study are obtained experimentally from the Autonomous University of the State of Quintana Roo, located on Mexico's southern border. The maximum power of the load is LPmax = 500 kW, and the average power is LPmean = 250 kW; the tariff of the electricity network operator has hourly conditions for a medium voltage demand. A suggested semi-empirical equation allows for determining the efficiency of the fuel cell and electrolyzer as a function of the local operating conditions and the nominal power of the components. The analytical strategy, the energy balance equations, and the identity functions that delimit the operating conditions are detailed to be generalized to other case studies. The results are obtained by a computer code programmed in C++ language. According to our boundary conditions, results show no significant savings generated by the installation of the hydrogen system when the zero-export photovoltaic system Power ≤ LPmax and DPP ≤ 20 years is possible only with LCOE ≤ 0.1 $/kWh. Specifically for the Mexico University case study, zero-export photovoltaic system cost must be less than 310 $/kW, fuel cell cost less than 395 $/kW, and electrolyzer cost less than 460 $/kW.