01
Photoelectrochemical CO2-to-Formic Acid Conversions: Advances in Photoelectrode Designs and Scale-Up Strategies
Bilawal Khan, M. Bilal Faheem, Karthik Peramaiah, Yuk-Tong Cheng, Bangul Khan, Quinn Qiao, Kuo-Wei Huang*, Jr-Hau He*.
Adv. Energy Mater.
https://doi.org/10.1002/aenm.202504018
Rapid decarbonization requires renewable technologies that convert carbon dioxide (CO2) into energy-dense, carbon-neutral fuels. Among those, photoelectrochemical CO2 conversion systems offer a direct and efficient pathway by coupling light-harvesting and electrocatalytic components within a single device. Among CO2-derived by-products, formic acid remains significant owing to its high volumetric energy density, liquid-phase storability, and transportable hydrogen carrier. This review outlines fundamental light-driven and catalytic processes of CO2-to-formic acid conversion and demonstrates its key performance merits. Device configuration of various photoelectrochemical CO2-to-formic acid conversion systems is analyzed with their recent advancements and bottlenecks. Despite significant progress of these systems, studies confirm that practical deployment remains limited by insufficient power output from photoelectrodes that limits bias-free operation, sluggish multi-electron kinetics that suppress conversion rates, and complex device architecture that hinders long-term and scale-up operation. Engineering and operational limitations that prevent photoelectrodes from bias-free operation, long-term stability, and efficient solar-to-fuel conversion efficiency are then investigated, and strategies to overcome these limitations are outlined. Furthermore, engineering strategies of compact electrolyzers are discussed to perform CO2-to-formic acid conversion under high light-intensity. Key considerations to overcome mass transport limitations and address downstream formic acid separation challenges are discussed to bridge gap between laboratory-scale demonstrations and real-world applications.
02
Fundamentals and environmental applications of bismuth vanadate through photoelectrocatalysis
Leonardo E. Navarrete-Cevallos, Ronald Vargas & Patricio J. Espinoza-Montero*.
npj Clean Water 2025, 8, 87.
https://doi.org/10.1038/s41545-025-00511-0
This review outlines the fundamentals of photoelectrocatalysis (PEC) using BiVO4 as a promising photoelectrode for environmental applications. Key PEC factors—light absorption, semiconductor properties, potential, temperature, and pH—are discussed. BiVO4’s optical, structural, and stability traits are compared with other vanadates. Synthesis methods (electrodeposition, SILAR, sputtering, and others) and performance-enhancing strategies (doping, heterojunctions, high-exposed facets) are examined. BiVO4’s pollutant degradation pathway and dual-function PEC systems are explored, emphasizing the balance between properties for efficient energy conversion and environmental cleanup.
