Transcriptomic insights unveil the crucial roles of cytochromes, NADH, and pili in Ag(I) reduction by Geobacter sulfurreducens.

Silver (Ag) is a pivotal transition metal with applications in multiple industries, necessitating efficient recovery techniques. Despite various proposed methods for silver recovery from wastewaters, challenges persist especially for low concentrations. In this context, bioreduction by bacteria like Geobacter sulfurreducens, offers a promising approach by converting Ag(I) to Ag nanoparticles. To reveal the mechanisms driving microbial Ag(I) reduction, we conducted transcriptional profiling of G. sulfurreducens under Ag(I)-reducing condition. Integrated transcriptomic and protein-protein interaction network analyses identified significant transcriptional shifts, predominantly linked to c-type cytochromes, NADH, and pili. When compared to a pilus-deficient strain, the wild-type strain exhibited distinct cytochrome gene expressions, implying specialized functional roles. Additionally, despite a down-regulation in NADH dehydrogenase genes, we observed up-regulation of specific downstream cytochrome genes, highlighting NADH's potential role as an electron donor in the Ag(I) reduction process. Intriguingly, our findings also highlight the significant influence of pili on the morphology of the resulting Ag nanoparticles. The presence of pili led to the formation of smaller and more crystallized Ag nanoparticles. Overall, our findings underscore the intricate interplay of cytochromes, NADH, and pili in Ag(I) reduction. Such insights suggest potential strategies for further enhancing microbial Ag(I) reduction.

Dynamic chloride ion adsorption on single iridium atom boosts seawater oxidation catalysis.

Seawater electrolysis offers a renewable, scalable, and economic means for green hydrogen production. However, anode corrosion by Cl- pose great challenges for its commercialization. Herein, different from conventional catalysts designed to repel Cl- adsorption, we develop an atomic Ir catalyst on cobalt iron layered double hydroxide (Ir/CoFe-LDH) to tailor Cl- adsorption and modulate the electronic structure of the Ir active center, thereby establishing a unique Ir-OH/Cl coordination for alkaline seawater electrolysis. Operando characterizations and theoretical calculations unveil the pivotal role of this coordination state to lower OER activation energy by a factor of 1.93. The Ir/CoFe-LDH exhibits a remarkable oxygen evolution reaction activity (202 mV overpotential and TOF = 7.46 O2 s-1) in 6 M NaOH+2.8 M NaCl, superior over Cl--free 6 M NaOH electrolyte (236 mV overpotential and TOF = 1.05 O2 s-1), with 100% catalytic selectivity and stability at high current densities (400-800 mA cm-2) for more than 1,000 h.

Efficient C-N coupling for urea electrosynthesis on defective Co3O4 with dual-functional sites.

Urea electrosynthesis under ambient conditions is emerging as a promising alternative to conventional synthetic protocols. However, the weak binding of reactants/intermediates on the catalyst surface induces multiple competing pathways, hindering efficient urea production. Herein, we report the synthesis of defective Co3O4 catalysts that integrate dual-functional sites for urea production from CO2 and nitrite. Regulating the reactant adsorption capacity on defective Co3O4 catalysts can efficiently control the competing reaction pathways. The urea yield rate of 3361 mg h-1 gcat-1 was achieved with a corresponding faradaic efficiency (FE) of 26.3% and 100% carbon selectivity at a potential of -0.7 V vs. the reversible hydrogen electrode. Both experimental and theoretical investigations reveal that the introduction of oxygen vacancies efficiently triggers the formation of well-matched adsorption/activation sites, optimizing the adsorption of reactants/intermediates while decreasing the C-N coupling reaction energy. This work offers new insights into the development of dual-functional catalysts based on non-noble transition metal oxides with oxygen vacancies, enabling the efficient electrosynthesis of essential C-N fine chemicals.

Effect of different hydrogen evolution rates at cathode on bioelectrochemical reduction of CO2 to acetate.

Microbial electrosynthesis (MES) offers a promising approach for converting CO2 into valuable chemicals such as acetate. However, the relative low conversion rate severely limits its practical application. This study investigated the impact of different hydrogen evolution rates on the conversion rate of CO2 to acetate in the MES system. Three potentials (-0.8 V, -0.9 V and -1.0 V) corresponding to various hydrogen evolution rates were set and analyzed, revealing an optimal hydrogen evolution rate, yielding a maximum acetate formation rate of 1410.9 mg/L and 73.5 % coulomb efficiency. The electrochemical findings revealed that an optimal hydrogen evolution rate facilitated the formation of an electroactive biofilm. The microbial community of the cathode biofilm highlighted key genera, including Clostridium and Acetobacterium, which played essential roles in electrosynthesis within the MES system. Notably, a low hydrogen evolution rate failed to provide sufficient energy for the electrochemical reduction of CO2 to acetate, while a high rate led to cathode alkalinization, impeding the reaction and causing significant energy wastage. Therefore, maintaining an appropriate hydrogen evolution rate is crucial for the development of mature electroactive biofilms and achieving optimal performance in the MES system.

Riboflavin-loaded carbon cloth aids the anaerobic digestion of cow dung by promoting direct interspecies electron transfer.

Cow dung generates globally due to increased beef and milk consumption, but its treatment efficiency remains low. Previous studies have shown that riboflavin-loaded conductive materials can improve anaerobic digestion through enhance direct interspecies electron transfer (DIET). However, its effect on the practical anaerobic digestion of cow dung remained unclear. In this study, carbon cloth loaded with riboflavin (carbon cloth-riboflavin) was added into an anaerobic digester treating cow dung. The carbon cloth-riboflavin reactor showed a better performance than other two reactors. The metagenomic analysis revealed that Methanothrix on the surface of the carbon cloth predominantly utilized the CO2 reduction for methane production, further enhanced after riboflavin addition, while Methanothrix in bulk sludge were using the acetate decarboxylation pathway. Furthermore, the carbon cloth-riboflavin enriched various major methanogenic pathways and activated a large number of enzymes associated with DIET. Riboflavin's presence altered the microbial communities and the abundance of functional genes relate to DIET, ultimately leading to a better performance of anaerobic digestion for cow dung.

Switching between C2+ Products and CH4 in CO2 Electrolysis by Tuning the Composition and Structure of Rare-Earth/Copper Catalysts.

Rational regulation of the reaction pathway to produce the desired products is one of the most significant challenges in the electrochemical CO2 reduction reaction (CO2RR). Herein, we designed a series of rare-earth Cu catalysts with mixed phases. It was found that the products could be switched from C2+ to CH4 by tuning the composition and structure of the catalysts. Particularly at the Cu/Sm atomic ratio of 9/1 (Cu9Sm1-Ox), the Faradaic efficiency (FE) for C2+ products (FEC2+) could reach 81% at 700 mA cm-2 with negligible CH4. However, the FE of CH4 (FECH4) was 65% at 500 mA cm-2 over Cu1Sm9-Ox (Cu/Sm = 1/9), and the FEC2+ was extremely low. Experiments and theoretical studies indicated that the stable CuSm2O4 phase existed in all the catalysts within the Cu/Sm range of 9/1 to 1/9. At a high Cu content, the catalyst was composed of CuSm2O4 and Cu phases. The small amount of Sm could enhance the binding strength of *CO and facilitate C-C coupling. Conversely, at a high Sm content, the catalyst was composed of CuSm2O4 and Sm2O3 phases. Sm could effectively stabilize bivalent Cu and enrich proton donors, lowering the reaction energy of *CO for deep hydrogenation to generate CH4. In both pathways, the stable CuSm2O4 phase could cooperate with the Cu or Sm2O3 phases, which induced the formation of different microenvironments to generate different products. This strategy also had commonality with other Cu-rare-earth (La, Pr, and Eu) catalysts to boost the CO2RR for C2+ or CH4 production.

Transcriptomic analysis reveals hub genes and pathways in response to acetic acid stress in Kluyveromyces marxianus during high-temperature ethanol fermentation.

The thermotolerant yeast Kluyveromyces marxianus is known for its potential in high-temperature ethanol fermentation, yet it suffers from excess acetic acid production at elevated temperatures, which hinders ethanol production. To better understand how the yeast responds to acetic acid stress during high-temperature ethanol fermentation, this study investigated its transcriptomic changes under this condition. RNA sequencing (RNA-seq) was used to identify differentially expressed genes (DEGs) and enriched gene ontology (GO) terms and pathways under acetic acid stress. The results showed that 611 genes were differentially expressed, and GO and pathway enrichment analysis revealed that acetic acid stress promoted protein catabolism but repressed protein synthesis during high-temperature fermentation. Protein-protein interaction (PPI) networks were also constructed based on the interactions between proteins coded by the DEGs. Hub genes and key modules in the PPI networks were identified, providing insight into the mechanisms of this yeast's response to acetic acid stress. The findings suggest that the decrease in ethanol production is caused by the imbalance between protein catabolism and protein synthesis. Overall, this study provides valuable insights into the mechanisms of K. marxianus's response to acetic acid stress and highlights the importance of maintaining a proper balance between protein catabolism and protein synthesis for high-temperature ethanol fermentation.

High-Rate CO2 Electrolysis to Formic Acid over a Wide Potential Window: An Electrocatalyst Comprised of Indium Nanoparticles on Chitosan-Derived Graphene.

Realizing industrial-scale production of HCOOH from the CO2 reduction reaction (CO2 RR) is very important, but the current density as well as the electrochemical potential window are still limited to date. Herein, we achieved this by integration of chemical adsorption and electrocatalytic capabilities for the CO2 RR via anchoring In nanoparticles (NPs) on biomass-derived substrates to create In/X-C (X=N, P, B) bifunctional active centers. The In NPs/chitosan-derived N-doped defective graphene (In/N-dG) catalyst had outstanding performance for the CO2 RR with a nearly 100 % Faradaic efficiency (FE) of HCOOH across a wide potential window. Particularly, at 1.2 A ⋅ cm-2 high current density, the FE of HCOOH was as high as 96.0 %, and the reduction potential was as low as -1.17 V vs RHE. When using a membrane electrode assembly (MEA), a pure HCOOH solution could be obtained at the cathode without further separation and purification. The FE of HCOOH was still up to 93.3 % at 0.52 A ⋅ cm-2 , and the HCOOH production rate could reach 9.051 mmol ⋅ h-1 ⋅ cm-2 . Our results suggested that the defects and multilayer structure in In/N-dG could not only enhance CO2 chemical adsorption capability, but also trigger the formation of an electron-rich catalytic environment around In sites to promote the generation of HCOOH.

Application of artificial intelligence-based methods in bioelectrochemical systems: Recent progress and future perspectives.

Bioelectrochemical Systems (BESs) leverage microbial metabolic processes to either produce electricity by degrading organic matter or consume electricity to assist metabolism, and can be used for various applications such as energy production, wastewater treatment, and bioremediation. Given the intricate mechanisms of BESs, the application of artificial intelligence (AI)-based methods have been proposed to enhance the performance of BESs due to their capability to identify patterns and gain insights through data analysis. This review focuses on the analysis and comparison of AI algorithms commonly used in BESs, including artificial neural network (ANN), genetic programming (GP), fuzzy logic (FL), support vector regression (SVR), and adaptive neural fuzzy inference system (ANFIS). These algorithms have different features, such as ANN's simple network structure, GP's use in the training process, FL's human-like thought process, SVR's high prediction accuracy and robustness, and ANFIS's combination of ANN and FL features. The AI-based methods have been applied in BESs to predict microbial communities, products or substrates, and reactor performance, which can provide valuable information and improve system efficiency. Limitations of AI-based methods for predicting and optimizing BESs and recommendations for future development are also discussed. This review demonstrates the potential of AI-based methods in optimizing BESs and provides valuable information for the future development of this field.

Construction of 3D copper-chitosan-gas diffusion layer electrode for highly efficient CO2 electrolysis to C2+ alcohols.

High-rate electrolysis of CO2 to C2+ alcohols is of particular interest, but the performance remains far from the desired values to be economically feasible. Coupling gas diffusion electrode (GDE) and 3D nanostructured catalysts may improve the efficiency in a flow cell of CO2 electrolysis. Herein, we propose a route to prepare 3D Cu-chitosan (CS)-GDL electrode. The CS acts as a "transition layer" between Cu catalyst and the GDL. The highly interconnected network induces growth of 3D Cu film, and the as-prepared integrated structure facilitates rapid electrons transport and mitigates mass diffusion limitations in the electrolysis. At optimum conditions, the C2+ Faradaic efficiency (FE) can reach 88.2% with a current density (geometrically normalized) as high as 900 mA cm-2 at the potential of -0.87 V vs. reversible hydrogen electrode (RHE), of which the C2+ alcohols selectivity is 51.4% with a partial current density of 462.6 mA cm-2, which is very efficient for C2+ alcohols production. Experimental and theoretical study indicates that CS induces growth of 3D hexagonal prismatic Cu microrods with abundant Cu (111)/Cu (200) crystal faces, which are favorable for the alcohol pathway. Our work represents a novel example to design efficient GDEs for electrocatalytic CO2 reduction (CO2RR).

p-d Orbital Hybridization Induced by p-Block Metal-Doped Cu Promotes the Formation of C2+ Products in Ampere-Level CO2 Electroreduction.

Large-current electrolysis of CO2 to multi-carbon (C2+) products is critical to realize the industrial application of CO2 conversion. However, the poor binding strength of *CO intermediates on the catalyst surface induces multiple competing pathways, which hinder the C2+ production. Herein, we report that p-d orbital hybridization induced by Ga-doped Cu (CuGa) could promote efficient CO2 electrocatalysis to C2+ products at ampere-level current density. It was found that CuGa exhibited the highest C2+ productivity with a remarkable Faradaic efficiency (FE) of 81.5% at a current density of 0.9 A/cm2, and the potential at such a high current density was -1.07 V versus reversible hydrogen electrode. At 1.1 A/cm2, the catalyst still maintained a high C2+ productivity with an FE of 76.9%. Experimental and theoretical studies indicated that the excellent performance of CuGa results from the p-d hybridization of Cu and Ga, which not only enriches reactive sites but also enhances the binding strength of the *CO intermediate and facilitates C-C coupling. The p-d hybridization strategy can be extended to other p-block metal-doped Cu catalysts, such as CuAl and CuGe, to boost CO2 electroreduction for C2+ production. As far as we know, this is the first work to promote electrochemical CO2 reduction reaction to generate the C2+ product by p-d orbital hybridization interaction using a p-block metal-doped Cu catalyst.

A crystal growth kinetics guided Cu aerogel for highly efficient CO2 electrolysis to C2+ alcohols.

To realize commercial CO2 electrochemical reduction to C2+ alcohols, the selectivity and production rate should be further improved. Establishing controllable surface sites with a favorable local environment is an interesting route to guide the C2+ pathway. Herein, we report a room-temperature one-step synthetic strategy to fabricate a highly stable Cu aerogel as an efficient CO2 reduction electrocatalyst. Controlling crystal growth kinetics using different reductants is an efficient strategy to modulate the nucleation and growth rate of Cu aerogels, enabling the creation of efficient surface sites for the C2+ pathway. Over the Cu aerogel obtained by reducing Cu2+ using a weak reductant (NH3·BH3), the faradaic efficiency of C2+ products could reach 85.8% with the current density of 800 mA cm-2 at the potential of -0.91 V vs. reversible hydrogen electrode, and the C2+ alcohol selectivity was 49.7% with a partial current density of 397.6 mA cm-2, while the Cu aerogel prepared using a strong reductant (NaBH4) was favorable to generating CO. Experimental and theoretical studies showed that the selectivity of the reaction depended strongly on the desorption and dimerization of *CO intermediates on the catalysts. The strong reductant induced a defective Cu surface that could facilitate the desorption of the *CO intermediate, subsequently producing CO, whereas the low defect Cu produced using a weak reductant could significantly enhance the selectivity for the C2+ product by improving *CO adsorption and the C-C coupling on the catalyst. This work opens a new way for constructing efficient electrocatalysts for CO2 electroreduction to C2+ alcohols.

Integrated analysis of transcriptomic and protein-protein interaction data reveals cadmium stress response in Geobacter sulfurreducens.

Bacteria have evolved several mechanisms to resist Cd toxicity, which are crucial for Cd detoxication and have the potential to be used for bioremediation of Cd. Geobacter species are widely found in anaerobic environments and play important roles in natural biogeochemical cycles. However, the transcriptomic response of Geobacter sulfurreducens under Cd stress have not been fully elucidated. Through integrated analysis of transcriptomic and protein-protein interaction (PPI) data, we uncovered a global view of mRNA changes in Cd-induced cellular processes in this study. We identified 182 differentially expressed genes (|log2(fold change)| > 1, adjusted P < 0.05) in G. sulfurreducens exposed to 0.1 mM CdCl2 using RNA sequencing (RNA-seq). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that CdCl2 significantly affected sulfur compound metabolic processes. In addition, through PPI network analysis, hub genes related to molecular chaperones were identified to play important role in Cd stress response. We also identified a Cd-responsive transcriptional regulator ArsR2 (coded by GSU2149) and verified the function of ArsR2-ParsR2 regulatory circuit in Escherichia coli. This study provides new insight into Cd stress response in G. sulfurreducens, and identified a potential sensor element for Cd detection.

The microbial diversity in industrial effluents makes high-throughput sequencing-based source tracking of the effluents possible.

In order to explore the microbial diversity in industrial effluents, and on this basis, to verify the feasibility of tracking industrial effluents in sewer networks based on sequencing data, we collected 28 sewage samples from the industrial effluents relative to four factories in Shenzhen, China, and sequenced the 16S rRNA genes to profile the microbial compositions. We identified 5413 operational taxonomic units (OTUs) in total, and found that microbial compositions were highly diverse among samples from different locations in the sewer system, with only 107 OTUs shared by 90% of the samples. These shared OTUs were enriched in the phylum of Proteobacteria, the families of Comamonadaceae and Pseudomonadaceae, as well as the genus of Pseudomonas, with both degradation related and pathogenic bacteria. More importantly, we found differences in microbial composition among samples relevant to different factories, and identified microbial markers differentiating effluents from these factories, which can be used to track the sources of the effluents. This study improved our understanding of microbial diversity in industrial effluents, proved the feasibility of industrial effluent source tracking based on sequencing data, and provided an alternative technique solution for environmental surveillance and management.

In situ dual doping for constructing efficient CO2-to-methanol electrocatalysts.

Methanol is a highly desirable product of CO2 electroreduction due to its wide array of industrial applications. However, the development of CO2-to-methanol electrocatalysts with high performance is still challenging. Here we report an operationally simple in situ dual doping strategy to construct efficient CO2-to-methanol electrocatalysts. In particular, when using Ag,S-Cu2O/Cu as electrocatalyst, the methanol Faradaic efficiency (FE) could reach 67.4% with a current density as high as 122.7 mA cm-2 in an H-type cell using 1-butyl-3-methylimidazolium tetrafluoroborate/H2O as the electrolyte, while the current density was below 50 mA cm-2 when the FE was greater than 50% over the reported catalysts. Experimental and theoretical studies suggest that the anion S can effectively adjust the electronic structure and morphology of the catalysts in favor of the methanol pathway, whereas the cation Ag suppresses the hydrogen evolution reaction. Their synergistic interactions with host material enhance the selectivity and current density for methanol formation. This work opens a way for designing efficient catalysts for CO2 electroreduction to methanol.

Design and Preparation of Electrocatalysts by Electrodeposition for CO2 Reduction.

With the increasing emission of carbon dioxide (CO2 ), the conversion and utilization of CO2 have become a topic of increasing concern. Electrochemical CO2 reduction reaction (CO2 RR) is an attractive and sustainable approach for solving energy and environmental problems. Design of efficient catalysts is crucial for achieving highly efficient CO2 RR. Different methods to prepare catalysts have been reported and used. Among them, electrodeposition is one of the common approaches, which has some obvious advantages, such as requiring simple equipment, environmentally benign. Especially, it can direct deposit catalysts on different substrates to prepare electrodes for CO2 RR. In this review, we discuss recent advances in design and preparation of the catalysts by electrodeposition and their applications in CO2 RR. Furthermore, the perspective of this promising area is also discussed.

Effect of applying potentials on anaerobic digestion of high salinity organic wastewater.

High salinity organic wastewater (HSOW) contains both organic pollutants and high concentration of inorganic salts. If it is discharged into the environment without proper treatment, it will cause adverse consequences such as dehydration and death of aquatic organisms, and soil salinization. Bioelectrochemical systems (BESs) have been applied in various wastewater treatment processes. To assess the feasibility of using BESs to treat HSOW, the effect of applying potential on anaerobic digestion of HSOW was explored in an up-flow anaerobic sludge blanket (UASB) reactor poised at -0.6 V (vs. Ag/AgCl). When organic loading rate (OLR) was 2.16-2.88 kg chemical oxygen demand/(m3d) (kg COD/(m3d)), the applied potential had no significant effect on the UASB performance. After OLR was increased to 4.32 kg COD/(m3d), the applied potential decreased COD removal efficiency and methane production and resulted in VFAs accumulation. Mesotoga was enriched on the electrode when potential was applied, causing decrease in relative abundances of acetoclastic methanogens. The abundance of Methanothrix on the electrode in the reactor with applied potential was much lower than in the control reactor (10% vs 28.9%), which might lead to decrease in performance of the reactor due to the depressed direct interspecies electron transfer (DIET) and less formation of granular sludge. These results suggest that applying external potentials has negative effect on the anaerobic treatment of HSOW, and should be taken into consideration in real HSOW treatment projects.

Iridium in Tungsten Trioxide Matrix as an Efficient Bi-Functional Electrocatalyst for Overall Water Splitting in Acidic Media.

Electrocatalytic water splitting in acidic media is a promising strategy for grid scale production of hydrogen using renewable energy, but challenges still exist in the development of advanced catalysts with both high activity and stability. Herein, it is reported that iridium doped tungsten trioxide (Ir-doped WO3 ) with arrayed structure and confined Ir sites is an efficient and durable bi-functional catalyst for overall acidic water splitting. A low overpotential (258 mV) is required to achieve an oxygen evolution reaction current density of 10 mA cm-2 in 0.5 m H2 SO4 solution. Meanwhile, Ir-doped WO3 processes a similar intrinsic activity to Pt/C toward hydrogen evolution reaction. Overall water splitting using the bi-functional Ir-doped WO3 catalyst shows low cell voltages of 1.56 and 1.68 V to drive the current densities of 10 and 100 mA cm-2 , respectively, with only 16 mV decay observed after 60 h continuous electrolysis under the current density of 100 mA cm-2 . Structural analysis and density functional theory calculation indicate that the adjusted coordination environment of Ir within the crystalline matrix of WO3 contributes to the high activity and durability.

Boosting CO2 Electroreduction over a Cadmium Single-Atom Catalyst by Tuning of the Axial Coordination Structure.

Guided by first-principles calculations, it was found that Cd single-atom catalysts (SACs) have excellent performance in activating CO2 , and the introduction of axial coordination structure to Cd SACs cannot only further decrease the free energy barrier of CO2 reduction, but also suppress the hydrogen evolution reaction (HER). Based on the above discovery, we designed and synthesized a novel Cd SAC that comprises an optimized CdN4 S1 moiety incorporated in a carbon matrix. It was shown that the catalyst exhibited outstanding performance in CO2 electroreduction to CO. The faradaic efficiency (FE) of CO could reach up to 99.7 % with a current density of 182.2 mA cm-2 in a H-type electrolysis cell, and the turnover frequency (TOF) value could achieve 73000 h-1 , which was much higher than that reported to date. This work shows a successful example of how to design highly efficient catalysts guided by theoretical calculations.

Layered double hydroxide-based electrocatalysts for the oxygen evolution reaction: identification and tailoring of active sites, and superaerophobic nanoarray electrode assembly.

The electrocatalytic oxygen evolution reaction (OER) is a critical half-cell reaction for hydrogen production via water electrolysis. However, the practical OER suffers from sluggish kinetics and thus requires efficient electrocatalysts. Transition metal-based layered double hydroxides (LDHs) represent one of the most active classes of OER catalysts. An in-depth understanding of the activity of LDH based electrocatalysts can promote further rational design and active site regulation of high-performance electrocatalysts. In this review, the fundamental understanding of the structural characteristics of LDHs is demonstrated first, then comparisons and in-depth discussions of recent advances in LDHs as highly active OER catalysts in alkaline media are offered, which include both experimental and computational methods. On top of the active site identification and structural characterization of LDHs on an atomic scale, strategies to promote the OER activity are summarised, including doping, intercalation and defect-making. Furthermore, the concept of superaerophobicity, which has a profound impact on the performance of gas evolution electrodes, is explored to enhance LDHs and their derivatives for a large scale OER. In addition, certain operating standards for OER measurements are proposed to avoid inconsistency in evaluating the OER activity of LDHs. Finally, several key challenges in using LDHs as anode materials for large scale water splitting, such as the issue of stability and the adoption of membrane-electrode-assembly based electrolysers, are emphasized to shed light on future research directions.