Piezo‐Electrocatalysis for CO₂ Reduction Driven by Vibration

Abstract

value-added chemical feedstocks. From this perspective, photocatalytic reduction of CO 2 into CO and hydrocarbon using solar energy attracts lots of attention and provides referential significance for scientists to store intermittent renewable energy in carbon-based fuels and chemicals. [2] However, the advanced photocatalysis technique cannot exert its action where light is unavailable. It is therefore imperative to explore more strategies to expand the sources of natural energy utilization to cope with the ever-increasing CO 2 emission.Besides solar energy, there are many other renewable energies existing in nature, for example, vibration, tidal, wind energy, and so on. [3] Piezoelectric materials with non-centrosymmetric structure allow conversion of energy from vibration to electricity and vice versa, that is, a piezoelectric effect. Recently, an emerging application of piezoelectric materials based on their coupling of piezoelectric effect and electrochemistry for redox reaction have been demonstrated to realize vibration energy harvesting, [4] which is termed as piezo-electrocatalysis. Hong and coworkers proposed a piezoelectrochemical mechanism for the direct conversion of mechanical energy to electrical energy and firstly used it for water splitting in 2010 [5] and subsequently dye degradation in 2012. [6] Initially, piezo-electrocatalysis does not receive considerable attention because neither its hydrogen amount produced from water splitting nor the degradation rate of dyes can match the performance of the extensively investigated photocatalysis at that time. [7] The occurrence of turning point is that a singlelayer MoS 2 possessing superior piezoelectric performance [8] is found to exhibit ultrahigh piezo-electrocatalytic dye degradation in 2016 and hydrogen evolution activity in 2020 by Wu and coworkers. [9,10] In their work, the whole dye degradation process takes dozens of seconds and the hydrogen amount reaches ≈4000 µmol g −1 h −1 , which is the record high value among the reported piezo-electrocatalytic performance at that moment and even exceeds some photocatalytic activities to a certain extent. [10] Owing to the immensely enhanced piezo-electrocatalytic activity, further efforts have been devoted to this emerging research area, accompanied by the discovery of new applications. Kubota and coworkers reported that a method for the redox-activation of small organic molecules in response to applied mechanical energy could be developed through the piezoelectric effect. [11] Wang and coworkers reported a piezoelectrocatalytic strategy for nondestructive tooth whitening With rising CO 2 emissions caused by the massive consumption of fossil fuels, it is highly desirable to develop strategies that adopt renewable energy to convert CO 2 into value-added chemical feedstocks. Over the past decades, photocatalytic reduction of CO 2 using light energy has attracted considerable attention. However, the advanced photocatalysis techniques cannot exert their action where light is unavailable. Here, a method f...

Enabling Internal Electric Fields to Enhance Energy and Environmental Catalysis

“…In addition, the low CO 2 affinity and the competitive HER pose great challenges in photocatalytic CO 2 reduction. [122] Generally, asymmetric structures can induce the formation of an internal electric field, and element doping is a common method to create asymmetry. For example, doping erbium (Er) into n-type NiO could twist the unit cell of NiO to decrease the symmetry, giving rise to the internal electric field for efficient charge carrier separation and migration.…”

Spatially Separated Redox Cocatalysts on Ferroelectric Nanoplates for Improved Piezophotocatalytic CO2 Reduction and H2O Oxidation

“…12−14 Generally, external mechanical force-induced lattice deformation of piezoelectric semiconductors with noncentrosymmetric crystal structures or units gives rise to piezopotentials with negative and positive charges distributed on the two opposite sides, separating free electrons and holes for CO 2 reduction and H 2 O oxidation half-reaction, respectively. 15,16 The fundamental weaknesses of piezocatalytic CO 2 fixation are the weak piezoelectric polarization and insufficient catalytic active sites of the semiconductor piezoelectrics.…”

“…With the increasing world population and expanding industrialization, excessive fossil-fuel consumption and rigorous global warming have promoted extensive research on renewable means of converting CO 2 to useful chemicals and fuels. , Solar-driven photocatalytic CO 2 reduction as a sustainable and environment-friendly strategy to supply clean energy and maintain carbon balance has attracted considerable attention. , To date, numerous light-harvesting semiconductors have been explored as catalysts for CO 2 photoreduction. − Nevertheless, the solar-to-chemical energy conversion efficiencies are basically restricted by serious electron–hole recombination and sluggish surface reaction kinetics, impeding their practical applications. , Another limitation of photocatalysis is its severe sensitivity to the availability of sunlight, hindering its popularization, particularly in dark environments or in the presence of cloud intermittency. Piezocatalysis, converting mechanical energy into chemical energy, provides another option for cost-effective and round-the-clock conversion of CO 2 to generate value-added products by directly harvesting weak and dispersive energy resources from the surrounding ambient environment, such as water flow, vibration, and noise. − Generally, external mechanical force-induced lattice deformation of piezoelectric semiconductors with noncentrosymmetric crystal structures or units gives rise to piezopotentials with negative and positive charges distributed on the two opposite sides, separating free electrons and holes for CO 2 reduction and H 2 O oxidation half-reaction, respectively. , The fundamental weaknesses of piezocatalytic CO 2 fixation are the weak piezoelectric polarization and insufficient catalytic active sites of the semiconductor piezoelectrics.…”

Revealing the stochastic kinetics evolution of photocatalytic CO2reduction

“…It is distinct from electro-catalysis, where a bias is applied to drive the directed motion of charge carriers. 19–21 Composite photocatalysts are proposed to form a built-in electric field for enhancing the migration and separation of charge carriers, which in effect regulates the randomness of charge carrier behaviors. 22–24 The surface active site is generally created by loading noble metals ( e.g.…”