Electrolysis

Electrolysis
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Name	Electrolysis
Type	Chemical process
Inventor	Alessandro Volta, Humphry Davy
Discovered	Late 18th century
Applications	Chlorine production, Aluminium, Hydrogen economy

Electrolysis is an electrochemical process that uses an external electrical current to drive non-spontaneous chemical reactions, typically decomposing compounds into constituent elements or ions. It underpins industrial operations such as Chlor-alkali process and Hall–Héroult process, and supports emerging technologies in Hydrogen economy and Power-to-X. The technique links developments in Batteries, Fuel cell, Industrial revolution, and modern Renewable energy deployment.

Introduction

Electrolysis originated from experimental work by Alessandro Volta and was advanced by Humphry Davy and Michael Faraday, whose laws quantified the relation between electric charge and substance mass deposited. Early industrial adoption occurred in the 19th century with processes at facilities run by companies such as Alcoa and innovations connected to the Second Industrial Revolution. Modern electrolysis is integral to sectors influenced by policy instruments like the Paris Agreement and programs led by entities such as the International Energy Agency.

Principles and Mechanisms

The process operates in an electrochemical cell comprising electrodes and an electrolyte where redox reactions occur: oxidation at the anode and reduction at the cathode. Quantitative description follows Faraday's laws of electrolysis, connecting charge, current, and molar amounts; kinetics are governed by concepts in Butler–Volmer equation and mass transport described in works related to Nernst equation and Diffusion. Electrode potentials reference standard values from compilations like the Pourbaix diagram series. Mechanistic understanding draws on contributions from researchers at institutions such as Max Planck Society and Massachusetts Institute of Technology.

Methods and Types

Common configurations include molten salt electrolysis used in the Hall–Héroult process for aluminium and aqueous electrolysis used in the Chlor-alkali process for chlorine and sodium hydroxide production. Variants include proton exchange membrane (PEM) electrolysis developed with input from laboratories at General Electric and Siemens, alkaline electrolysis popularized by firms like Norsk Hydro, and solid oxide electrolysis cells (SOEC) researched at Oak Ridge National Laboratory and Fraunhofer Society. Other specialized methods encompass molten carbonate electrolysis applied in materials research at Argonne National Laboratory and high-pressure electrolyzers trialed in projects funded by the European Commission. Laboratory-scale techniques reference apparatus used in studies at University of Cambridge and Stanford University.

Applications

Industrial-scale electrolysis supports production of elemental gases and metals: hydrogen for fertiliser synthesis linked to the Haber–Bosch process, chlorine for chemical feedstocks tied to companies like Dow Chemical Company, and aluminium from bauxite processed by firms such as Rio Tinto. Electrolytic refining improves metal purity in operations by corporations like Freeport-McMoRan. In energy systems, electrolysis enables coupling of intermittent Wind power and Photovoltaics to chemical storage in projects led by utilities including Ørsted and Iberdrola. Emerging uses include synthetic fuels in consortium projects involving Shell and TotalEnergies, and oxygen production for aerospace missions coordinated by agencies such as NASA and European Space Agency.

Materials and Cell Design

Electrode and electrolyte selection determines performance: noble-metal catalysts (e.g., Platinum, Iridium) are used in PEM cells; non-precious catalysts investigated at institutions like University of Oxford aim to reduce reliance on strategic materials. Membranes such as Nafion were developed by firms like DuPont, while ceramic electrolytes in SOEC derive from research at Tokyo Institute of Technology. Cell architecture ranges from bipolar plate stacks commercialized by manufacturers such as Ballard Power Systems to planar microelectrodes employed in microfabrication labs at Harvard University. Material degradation and corrosion issues are addressed by standards bodies including International Electrotechnical Commission and testing programs at National Institute of Standards and Technology.

Efficiency, Economics, and Environmental Impact

Thermodynamic limits relate to reversible cell voltages identified in classical studies and contemporary analyses by think tanks like McKinsey & Company and agencies such as the International Renewable Energy Agency. Economic feasibility depends on capital expenditure trends driven by supply chains involving companies like Tesla, Inc. for electrical components and commodity markets for materials tracked by London Metal Exchange. Environmental assessments consider life-cycle impacts evaluated in reports from Intergovernmental Panel on Climate Change and contamination risks managed under frameworks like the Stockholm Convention for persistent pollutants. Policy, market incentives, and technological innovation by research consortia including H2Global and projects funded under Horizon Europe influence adoption trajectories.

Category:Electrochemical processes