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Fuel cells operated with a reformate fuel such as methanol are promising power systems for portable electronic devices due to their high safety, high energy density and low pollutant emissions. However, several critical issues including methanol crossover effect, CO-tolerance electrode and efficient oxygen reduction electrocatalyst with low or non-platinum usage have to be addressed before the direct methanol fuel cells (DMFCs) become commercially available for industrial application. Here, we report a highly active and selective Mg−Co dual-site oxygen reduction reaction (ORR) single atom catalyst (SAC) with porous N-doped carbon as the substrate. The catalyst exhibits a commercial Pt/C-comparable half-wave potential of 0.806 V (versus the reversible hydrogen electrode) in acid media with good stability. Furthermore, practical DMFCs test achieves a peak power density of over 200 mW cm−2 that far exceeds that of commercial Pt/C counterpart (82 mW cm−2). Particularly, the Mg−Co DMFC system runs over 10 h with negligible current loss under 10 M concentration methanol work condition. Experimental results and theoretical calculations reveal that the N atom coordinated by Mg and Co atom exhibits an unconventional d -band-ditto localized p -band and can promote the dissociation of the key intermediate *OOH into *O and *OH, which accounts for the near unity selective 4e− ORR reaction pathway and enhanced ORR activity. In contrast, the N atom in SAC Co remains inert in the absorption and desorption of *OOH and *OH. This local coordination environment regulation strategy around active sites may promote rational design of high-performance and durable fuel cell cathode electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO 2 reduction reaction (CO 2 RR) to produce multi-carbon products (C 2+) 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 C 2+ production. However, it still lacks effective strategies to controllably synthesize abundant GBs, rendering efficient C 2+ 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 C 2+ faradaic efficiency of ca. 70.0 % in H-type cell and 68.2 % in flow cell; even more impressively, it delivers an ultra-high C 2+ current density of 0.768 A cm−2, outperforming most recently reported results. A combination of in situ spectroscopies 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 C 2+ production performance. [Display omitted] • An unconventional grain fragmentation strategy is proposed to controllably tune the density of Cu GBs. • The optimal catalyst exhibits a C 2+ current density of 0.768 A cm−2, outperforming most reported counterparts. • The high C 2+ production stems from a higher *CO coverage and more facile *CO-*CO coupling over Cu GBs. [ABSTRACT FROM AUTHOR]

Rational design of highly efficient photocatalysts for CO 2 conversion 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-C 3 N 4) has been widely used in photocatalytic CO 2 reduction (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-C 3 N 4 /β-Bi 2 O 3 heterojunction photocatalyst based on self-assembly of nitrogen vacancies in g-C 3 N 4 nanosheets and β-Bi 2 O 3 micro-flowers, yielding an enhanced CO evolution rate of 30.56 μmol·g−1·h−1 under 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-C 3 N 4 (N V -C 3 N 4), 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 CO 2 photoreduction to solar fuels. [Display omitted] • Synergistic nitrogen vacancy and Z-scheme heterojunction strategy are introduced in g-C 3 N 4 /β-Bi 2 O 3 photocatalysts. • Newfangled dynamic evolution of nitrogen vacancy boosts the intrinsic activity. • Unique Z-scheme heterojunction greatly promotes the charge separation ability. • In situ DRIFT and DFT simulation uncover the mechanisms of CO 2 photoreduction. [ABSTRACT FROM AUTHOR]

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 CO 2 piezo-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. [Display omitted] • A dynamic strain engineering strategy for periodically tailoring adsorption between catalysts and intermediates is proposed. • This strategy eliminates the bygone need for complex catalyst synthesis and can be universally applied to any catalyst. • The underlying mechanism for the enhanced CO 2 conversion via such strategy is investigated. [ABSTRACT FROM AUTHOR]

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. Image 1 • Bi-harvesting light/vibration energy using hydrothermally-synthesized ZnO nanorods is realized. • Bi-catalysis for dye decomposition is better than photocatalysis or piezocatalysis alone. • ZnO is potential for dye wastewater remediation through harvesting ambient light/vibration energy. [ABSTRACT FROM AUTHOR]

Piezo-electrocatalytic CO 2 reduction reaction (PECRR) technique has been verified as an effective CO 2 -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 BaTiO 3 and graphene oxide (GO) as a demonstration. With an optimized GO concentration, the BaTiO 3 shows a CO yield of 134.4 μmol g−1 h−1 which is about 45.3 % higher than that of pristine BaTiO 3. The mechanisms for the enhancement are revealed via boosted piezo-carrier dynamics and charge transfer from BaTiO 3 to GO as well as enhanced intrinsic activity. Furthermore, physical mixing of GO is extended to other piezo-electrocatalysts (MoS 2 , ZnO, ZnS, CdS, Bi 2 WO 6), 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. [Display omitted] • A facile physical mixing method boosting piezo-electrocatalytic CO 2 conversion performance is reported. • Charge transfer behavior between BaTiO 3 and graphene oxide is evidenced via a piezo-deposition experiment. • The method shows great potential in general large-scale preparation of high-performance and low-cost piezo-electrocatalyst. [ABSTRACT FROM AUTHOR]

The development of advanced photocatalysts for CO 2 reduction (CO 2 R) 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 Bi 5 O 7 Br 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 CO 2 and the formation of key intermediates. Ultimately, an ultrahigh CO yield rate of 30.96 μmol g−1 h−1 was 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. [Display omitted] • Atomic "-Bi-O-Br-" concave engineering is introduced in Bi 5 O 7 Br photocatalysts. • Charge localization induced by concave greatly enhanced CO 2 capture capacity. • Multifunctional improvement of carrier dynamics and surface reaction is achieved. • In situ DRIFT and DFT simulation uncover the mechanisms of CO 2 photoreduction. [ABSTRACT FROM AUTHOR]

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 TiO 2 enables a higher activity towards hydrogen evolution from water splitting than corresponding single site, we successfully synthesized a Cu 1 -Ti dual-site catalyst by depositing Cu single atoms on TiO 2 nanoparticles with abundant surface oxygen vacancies. The designed target catalyst significantly outperforms the benchmark Pt nanoparticle decorated TiO 2 with a high and stable activity towards photocatalytic hydrogen production. [Display omitted] • Theoretical calculations revealed that Ovs promote water dissociation and single Cu atoms promote hydrogen evolution. • The designed target catalyst exhibited extraordinarily high activity and excellent stability for photocatalytic H 2 evolution. • The method provide a paradigm that precisely combines single atoms with substrate metal sites to generate active dual sites. [ABSTRACT FROM AUTHOR]

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 (k ET) and efficiency (η ET) are 3.658 × 106s−1 and 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 CO 2 photoreduction 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. The (010)/(102) facet junction on the BiOBr nanosheet was used for efficient charge separation and transport. its fast electron transfer rate and high transfer efficiency result in the high CO evolution rate from CO 2 photoreduction under artificial sunlight. Our work may bring some new insights into the mechanism understanding of facet junction and rational design of photocatalysts with high performance for solar energy storage in future. [Display omitted] • BiOBr nanosheets with different facet junctions were synthesized for photocatalytic CO 2 reduction. • The (010)/(102) facet junction presents more favorable charge separation and transfer performance than (001)/(110). • Such charge separation in (010) / (102) facet junction facilitates the efficient conversion of CO 2 into CO. [ABSTRACT FROM AUTHOR]

In the suspensions with the Ba 0.75 Sr 0.25 TiO 3 (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 •O 2 − 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. Image 1 • Tribocatalytic dye decomposition of Ba 0.75 Sr 0.25 TiO 3 nanoparticles is realized in suspensions under friction. • Dye decomposition efficiency can be greatly improved through some modifications in stirring rods. • The tribocatalysis is originated from the triboelectricity between Ba 0.75 Sr 0.25 TiO 3 nanoparticles and plastic rods. • The novel tribocatalysis is potential in wastewater treatment through harvesting environmental frication energy. [ABSTRACT FROM AUTHOR]