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Photoelectrochemical splitting of water into hydrogen is a potential route to motivate the application of solar-driven conversion to clean energy but is regularly limited by its low efficiency. The key to addressing this issue is to design a suitable photocathode configuration for high-efficiency photogenerated carrier separation and transmission to photocathode-surface reaction sites. In this work, we report a Si-Cu2O tandem photocathode featuring a p-n-p configuration for solar-driven hydrogen evolution in an alkaline solution. Driven by this built-in field, the electrons induced from Si were transferred through FeOOH, which acted as electron tunnels, to combine with the holes from Cu2O, triggering more electrons generated from Cu2O to particiate in the surface reaction. Under simulated sunlight, the optimized photocathode achieved and maintained a photocurrent density of −11 mA/cm2at 0 VRHEin alkaline conditions for 120 min, outperforming the reported tandem cell consisting of Si and Cu2O photocathodes. Our results provide valuable insight into a feasible way to construct an optimized photocathode for efficient solar-driven H2evolution.

Fluoroarene (FA) derivatives are persistent, toxic, and bioaccumulative pollutants, which pose severe risks to ecosystems and human health. Efficient cleavage of C–F bonds and complete mineralization of defluorinated intermediates are the keys for the deep treatment of FAs due to the high dissociation energy of C–F bonds and the high stability of aromatic rings. Herein, we report a synchronous defluorination-oxidation process using a photoelectrocatalytic device with a TiO2photoanode, in which FAs are selectively cleavage of C–F bonds by photolysis and subsequently efficient oxidized by on-site generated •OH radical. Complete defluorination and mineralization (both over 99.9%) of 4-fluorophenol are achieved under irradiation at 1.0 VRHEin 120 min, the apparent reaction rate constant is 14.4 g h−1m−2. This synchronous defluorination-oxidation process provides an efficient and practical technique for the mineralization of FAs in wastewater under mild conditions.

Electrocatalytic CO2reduction reaction (CO2RR) to produce multi-carbon products (C2+) is one of the most sustainable manners to achieve net-zero carbon emissions. Among many approaches, enriching grain boundaries (GBs) in copper (Cu) catalysts has been demonstrated to enable enhancement for C2+production. However, it still lacks effective strategies to controllably synthesize abundant GBs, rendering efficient C2+production a persistent challenge, especially at ampere-level current density. Herein, we propose a novel strategy, which can achieve unconventional grain fragmentation during thermal annealing and thus create controllable GB densities. The catalyst with the utmost GB density exhibits a peak C2+faradaic efficiency of ca.70.0 % in H-type cell and 68.2 % in flow cell; even more impressively, it delivers an ultra-high C2+current density of 0.768 A cm−2, outperforming most recently reported results. A combination of in situspectroscopies and theoretical calculations reveal that the enrichment of GBs yields more active sites for a higher *CO coverage, leading to promotion of the *CO-*CO coupling process and ultimately high C2+production performance.

A critical bottleneck for realizing an efficient Schottky type Si photoelectrode is minimizing the charge extraction losses across the heterointerface via reducing the unfavorite defects. This requires a clear microscopic insight into the correlation between interfacial features and photoconversion. Herein, by taking the n-Si/oxide (MOx)/Ni as the prototype, the heterointerface with the different characteristics and its effects on charge transportation and the corresponding photoelectric/photoelectrochemical (PEC) behaviors were clarified. An ultra-thin AlOxlayer can effectively diminish the interfacial pinning of n-Si/Ni and significantly facilitate the photoconversion; meanwhile, it results in some unexpected donor-like deep defects at around 0.59 eV below the conduction band of n-Si, which could be ionized under a reverse bias and cause about 10% photogenerated charge recombination. Fortunately, these deep defects can be further eliminated by cooperating AlOxwith a thin Au layer. The AlOx/Au dual-interlayer can remove almost all unexpected defects and maximize the efficiency of the electric field for charge extraction from semiconductor Si for the surface catalytic reaction. Eventually, the n-Si/SiOx/AlOx/Au/Ni/NiFeOxphotoanode exhibited a record fill factor of 0.75 for the corresponding photoelectric device and an applied bias photon-to-current efficiency of 3.71% for PEC water oxidation. This study provides definite insights into interfacial electronic states and elaborates their crucial role in solar photoelectric conversion.

Rational design of highly efficient photocatalysts for CO2conversion into carbonaceous fuels is of great significance to mitigate the global greenhouse effect and energy shortage problem. Among numerous materials studied for this purpose, the carbon nitride (g-C3N4) has been widely used in photocatalytic CO2reduction (PCR) due to its decent optical properties, low cost and environment friendliness. However, its wide use still remains a substantial challenge due to inefficiency of the active site and rapid recombination of photogenerated electrons and holes. Herein, we suggest a Z-scheme system of nitrogen vacancies g-C3N4/β-Bi2O3heterojunction photocatalyst based on self-assembly of nitrogen vacancies in g-C3N4nanosheets and β-Bi2O3micro-flowers, yielding an enhanced CO evolution rate of 30.56 μmol·g−1·h−1under the simulated solar light without any cocatalysts and sacrificial agents. Our detailed studies indicate that the promoted PCR performance originates from the stronger adsorption capability of the *COOH intermediates due to the cleavage of the C-C bond in nitrogen vacancies g-C3N4(NV-C3N4), turning the most endothermic step from the formation of *COOH intermediates to *CO. Moreover, the unique Z-scheme feature can efficiently facilitate the separation of photoelectron-hole pairs and enhance redox capability by optimizing the energy band structure. To sum up, this work provides deep insights and guidelines for rational design of highly efficient Z-scheme heterojunctions catalysts for CO2photoreduction to solar fuels.

Strain engineering involves intentionally inducing lattice distortion in materials to manipulate their electronic and geometric properties, along with the accompanying bond strength between reactants and catalysts. This approach presents an appealing pathway to optimize catalytic performance. However, it confronts challenges in achieving precise control, scalability and controllable modulation of intermediate species’ adsorption and desorption. Herein, we report a dynamic strain engineering method achieved through ultrasonic cavitation-induced high and low-pressure cycles, enabling periodically adjustable adsorption/desorption properties while bypassing complex synthesis procedures. Illustrated using ZnO and CO2piezo-reduction reaction as a demonstration, theoretical studies initially predict that adsorption of intermediates *COOH can be regulated within a specific range of strains. Under ultrasonic stimulation, ZnO catalyst with dynamic strain engineering exhibits a CO yield of ∼ 98.8 μmol·g−1·h−1, approximately 16.5 times higher than that achieved under ultraviolet light irradiation without dynamic strain engineering, despite the latter having a considerably stronger input power. Furthermore, we delve into the factors linked to dynamic strain amplitude and frequency. This dynamic strain engineering approach streamlines catalyst preparation and presents innovative possibilities for controlled manipulation of intermediate specie’s adsorption/desorption, with potential applications across a wide range of catalytic systems.

Piezo-electrocatalytic CO2reduction reaction (PECRR) technique has been verified as an effective CO2-to-fuel conversion strategy by exploiting and utilizing the widely distributed mechanical energy in nature, e.g., blue energy. The facile large-scale preparation of high-performance and low-cost piezo-electrocatalysts is therefore highly desired but challenging. Herein, a method of physical mixing of piezo-electrocatalysts and earth-abundant carbon-based materials is proposed to address the above issue, and we verified this method with typical piezoelectric BaTiO3and graphene oxide (GO) as a demonstration. With an optimized GO concentration, the BaTiO3shows a CO yield of 134.4 μmol g−1h−1which is about 45.3 % higher than that of pristine BaTiO3. The mechanisms for the enhancement are revealed via boosted piezo-carrier dynamics and charge transfer from BaTiO3to GO as well as enhanced intrinsic activity. Furthermore, physical mixing of GO is extended to other piezo-electrocatalysts (MoS2, ZnO, ZnS, CdS, Bi2WO6), from which it is found that their performance is improved compared to the counterpart of those without GO. This work suggests that the physical mixing GO is a universal method to improve PECRR performance and may be a decent candidate approach for large-scale preparation of high-performance and low-cost piezo-electrocatalysts in future.

In this work, the bi-harvesting of light and vibration energy is realized in hydrothermally-synthesized ZnO nanorods which is designed to achieve photo-/piezo-bi-catalysis for dye decomposition. In the presence of both UV irradiation and vibration, the decomposition ratio of ZnO nanorods for acid orange 7 is ∼80.8% within 100 min, which is higher than the value of ∼56.7% for photo-catalysis or the value of ∼31.8% for piezocatalysis. The enhanced photo-/piezo-bi-catalysis of ZnO nanorods in dye decomposition can be attributed to that the piezoelectric potential which formed in piezocatalysis process can help separate the photogenerated electron-hole pairs, therefore achieving a synergy effect between photocatalysis and piezocatalysis. The excellent photo-/piezo-bi-catalysis of ZnO can potentially find application in enhancing catalytic efficiency of dye decomposition through harvesting the light and vibration energy present in natural environments.

The development of advanced photocatalysts for CO2reduction (CO2R) has attracted intensive interest but is severely plagued by the intrinsically narrow photo-responsive range, inefficient carrier separation of the current supports. Herein, the unconventional atomic surface concaves with Bi-O-Br complex vacancies on thin Bi5O7Br nanotubes were designed and successfully synthesized. This concave-rich structures provide electron localized enrichment regions that could address the above two issues simultaneously. The unique concaves serve as the active sites that enable the exceptional capacity for the capture and activation of CO2and the formation of key intermediates. Ultimately, an ultrahigh CO yield rate of 30.96 μmol g−1h−1was obtained under ambient conditions without anchoring extra metal active species or any sacrificial agents. Our work not only provides a promising support but also proposes a unique structure to optimize the photocatalytic performance.

Constructing dual sites is promising to break scaling relations between the adsorption energetics of reaction intermediates and ultimately improves the activity and selectivity due to the synergistic effect. However, it is a grand challenge to precisely form a dual-site configuration with one metal site adjacent to another active site. Loading single atoms onto oxides with pre-introduction of surface oxygen vacancies may be an alternative strategy to overcome such challenge. Motivated by our theoretical calculations that the dual sites formed by single Cu atoms and unsaturated Ti sites on TiO2enables a higher activity towards hydrogen evolution from water splitting than corresponding single site, we successfully synthesized a Cu1-Ti dual-site catalyst by depositing Cu single atoms on TiO2nanoparticles with abundant surface oxygen vacancies. The designed target catalyst significantly outperforms the benchmark Pt nanoparticle decorated TiO2with a high and stable activity towards photocatalytic hydrogen production.

The g-C3N4isotype heterojunction was synthesized for photocatalytic CO2reduction, which exhibits an impressive activity and outstanding stability.The isotype heterojunction presents more favorable charge separation and transfer performance than the single components.The enhanced photogenerated charge dynamics in isotype heterojunction facilitates the production of key intermediates and thus the whole reaction kinetics.

Understanding on the photogenerated charge separation from a microscopic level remains a challenge and is highly desirable as it provides a cornerstone for designing high-performance photocatalysts. Herein, facet engineering is chosen as a tool to reveal the relationship between the charge separation/transfer and crystal structure. A series of BiOBr nanosheets with dominantly exposed facet of (001) or (010) as well as different lateral facet exposure ratios are constructed via adjusting pH value during the hydrothermal process. It is found that exposure of anisotropic crystal facets allows the separative transfer of photogenerated electrons and holes onto the lateral facets and dominantly exposed facets, respectively, which is attributed to the junction formed between distinct facets (i.e., facet junction). In the case of BiOBr-5 with (010)/(102) facet junction, the electron transfer rate (kET) and efficiency (ηET) are 3.658 × 106s−1and 54.09%, which are superior than the counterpart of BiOBr-1 with (001)/(110) facet junction. The fast electron transfer rate and high transfer efficiency of BiOBr-5 result in the high CO evolution rate from CO2photoreduction under artificial sunlight. Our work may bring some new insights into the mechanism of facet junction and rational design of photocatalysts with high performance for solar energy storage in future.

In the suspensions with the Ba0.75Sr0.25TiO3(BST) nanoparticles with an average size ~20 nm for triboelectric energy harvesting, dye decompositions were found to occur readily in the course of a normal stirring in dark at room temperature. More importantly, the decomposition efficiency can be greatly improved through some simple modifications in stirring rods and as high as 99.0% Rhodamine B can be decomposed in 3 h under a mild stirring of 300 rpm. Some well-designed experiments have been conducted, which show that the observed dye decompositions are directly related to the friction between BST nanoparticles and stirring rods in magnetic stirring. It is proposed that with the mechanical energy absorbed from friction, the BST nanoparticles have exerted a novel tribocatalytic effect for dye decompositions, which is confirmed by the detection of intermediate products of •OH and •O2−in stirring. These results clearly demonstrate that nanostructured oxides have the capability to harvest mechanical energy from ambient environment through friction for dye decomposition, which represents an important application for harvesting mechanical friction energy.