The storage/utilization of solar energy is a promising strategy to alleviate current disparities in energy shortage Direct conversion of solar light into chemical energy by means of photocatalysis or photoelectrocatalysis is currently a point of focus for sustainable energy development and environmental remediation. However, its current efficiency is still far from satisfying, suffering especially from severe charge recombination. To solve this problem, the piezo-phototronic effect has emerged as one of the most effective strategies for photo(electro)catalysis. Through the integration of piezoelectricity, photoexcitation, and semiconductor properties, the built-in electric field by mechanical stimulation induced polarization can serve as a flexible autovalve to modulate the charge-transfer pathway and facilitate carrier separation both in the bulk phase and at the surfaces of semiconductors. This review focuses on illustrating the trends and impacts of research based on piezo-enhanced photocatalytic reactions. The fundamental mechanisms of piezo-phototronics modulated band bending and charge migration are highlighted. Through comparing and classifying different categories of piezo-photocatalysts (like the typical ZnO, MoS 2 , and BaTiO 3 ), the recent advances in polarization-promoted photo(electro)catalytic processes involving water splitting and pollutant degradation are overviewed. Meanwhile the optimization methods to promote their catalytic activities are described. Finally, the outlook for future development of polarization-enhanced strategies is presented.
Ferric oxides and (oxy)hydroxides, although plentiful and low‐cost, are rarely considered for oxygen evolution reaction (OER) owing to the too high spin state (eg filling ca. 2.0) suppressing the bonding strength with reaction intermediates. Now, a facile adsorption–oxidation strategy is used to anchor FeIII atomically on an ultrathin TiO2 nanobelt to synergistically lower the spin state (eg filling ca. 1.08) to enhance the adsorption with oxygen‐containing intermediates and improve the electro‐conductibility for lower ohmic loss. The electronic structure of the catalyst is predicted by DFT calculation and perfectly confirmed by experimental results. The catalyst exhibits superior performance for OER with overpotential 270 mV @10 mA cm−2 and 376 mV @100 mA cm−2 in alkaline solution, which is much better than IrO2/C and RuO2/C and is the best iron‐based OER catalyst free of active metals such as Ni, Co, or precious metals.
The excessive dependence on fossil fuels contributes to the majority of CO2 emissions, influencing on the climate change. One promising alternative to fossil fuels is green hydrogen, which can be produced through water electrolysis from renewable electricity. However, the variety and complexity of hydrogen evolution electrocatalysts currently studied increases the difficulty in the integration of catalytic theory, catalyst design and preparation, and characterization methods. Herein, this review first highlights design principles for hydrogen evolution reaction (HER) electrocatalysts, presenting the thermodynamics, kinetics, and related electronic and structural descriptors for HER. Second, the reasonable design, preparation, mechanistic understanding, and performance enhancement of electrocatalysts are deeply discussed based on intrinsic and extrinsic effects. Third, recent advancements in the electrocatalytic water splitting technology are further discussed briefly. Finally, the challenges and perspectives of the development of highly efficient hydrogen evolution electrocatalysts for water splitting are proposed.
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