ZnO-templated hollow amorphous carbon: oxygen adsorption and doping synergy for enhanced ORR catalysis.

In pursuit of highly active zinc-air battery (ZAB) catalysts, nitrogen doping has proven key to enhancing carbon-based non-metallic catalysts' performance in the oxygen reduction reaction (ORR). This study employed a novel method to synthesize variously sized ZnO materials coated with ZIF-8. Notably, smaller particle sizes correlated with reduced activation energy. ZnO-12, the smallest variant, fully carbonized at 800 °C, resulting in zinc ion evaporation and the formation of an amorphous carbon nano-hollow structure, ZIF8/ZnO-12. This material showcased remarkable ORR properties, with an onset potential of 0.9 V (vs. RHE) and a Tafel slope of 71.4 mV dec-1, surpassing the benchmark Pt/C catalyst and exhibiting excellent stability. Moreover, in ZAB tests, ZIF8/ZnO-12 achieved a specific capacity of 816 mA h g-1, outperforming Pt/C. DFT calculations indicate that under alkaline conditions, nitrogen-doped carbon materials containing adsorbed oxygen and doped oxygen exhibit lower catalytic activation energy for the ORR, which is beneficial for accelerating the ORR. This research provides valuable insights into designing more efficient carbon-based non-metallic catalysts for ZABs.

Water-soluble fullerenol-mediated electron transfer in molecular systems toward enhanced solar hydrogen production.

We present here that visible-light-induced electron transfer from an excited dye to an in situ generated Pt cocatalyst can be promoted by employing water-soluble fullerenol (C60(OH)24) as an electron mediator, and as a result, the fullerenol-based molecular system shows a 3 times higher H2 evolution activity than C60(OH)24-free system.

A Cu hollow fiber with coaxially grown Bi nanosheet arrays as an integrated gas-penetrable electrode enables high current density and durable formate electrosynthesis.

While high current density formate (HCOO-) electrosynthesis from CO2 reduction has been achieved in a flow cell assembly, the inevitable flooding and salt precipitation of traditional gas-diffusion electrodes (GDEs) severely limit the overall energy efficiency and stability. In this work, an integrated gas-penetrable electrode (GPE) for HCOO- electrosynthesis was developed by coaxially growing vertically aligned high density Bi nanosheet arrays on a porous Cu hollow fiber (Bi NSAs@Cu HF) via controllable galvanic replacement. The interior porous Cu HF serves as a robust gas-penetrable and conductive host for continuously delivering CO2 gas to surface-anchored Bi NSAs, resulting in numerous well-balanced triphase active interfaces for the electrocatalytic CO2 reduction reaction (CO2RR). The most active Bi NSAs@Cu HF GPE exhibits a high HCOO- faradaic efficiency (FEHCOO-) of over 80% in a wide potential window (330 mV) with a linearly increased partial current density (jHCOO-) up to -261.6 mA cm-2 at -1.11 V vs. the reversible hydrogen electrode (RHE). The Bi NSAs@Cu HF GPE also sustains a FEHCOO- of >80% at a high total current density of -300 mA cm-2, corresponding to a jHCOO- of >-240 mA cm-2, for more than 60 h. This work provides new perspectives on designing efficient and durable integrated GPEs for a sustainable CO2RR on a large scale.

An in situ exsolved Cu-based electrocatalyst from an intermetallic Cu5Si compound for efficient CH4 electrosynthesis.

A Cu-based electrocatalyst (e-Cu5Si) is developed by in situ exsolving ultrathin SiOx layer-coated CuO/Cu nanoparticles (<100 nm) on the surface of a conductive intermetallic Cu5Si parent. This specially designed e-Cu5Si catalyst exhibits high performance for the CO2 reduction reaction (CO2RR), which affords an excellent CH4 faradaic efficiency (FE) of 49.0% with partial current density of over 140.1 mA cm-2 at -1.2 V versus reversible hydrogen electrode (RHE) in a flow cell, with outstanding stability. The strongly coupled multiphase interfaces among the SiOx layer, CuO/Cu species, and substrate contribute to fast interfacial electron transfer for the CO2RR. Moreover, in situ Raman analysis suggests that the ultrathin SiOx layer simultaneously stabilizes the active Cu1+ species and promotes the protonation of *CO to form *CHxO, thereby greatly improving overall selectivity and activity of CH4 production.

A hierarchical carbon foam-hosted Co2P nanoparticles monolithic electrode for ampere-level and super-durable electrocatalytic hydrogen production.

In this work, we develop a hierarchical carbon foam-based monolithic electrode (Co2P@HCF) from Co2+-adsorbed polyvinyl alcohol (PVA) sponge via the successive carbonization and phosphorization. Owing to the 3D hierarchical porous structure, excellent electrolyte wettability, good mechanical strength, and intimate embedding of highly dispersed Co2P nanoparticles, the Co2P@HCF electrode delivers a high current density of 1.0 A cm-2 for the hydrogen evolution reaction (HER) at ultralow overpotentials of 189.6 and 218.6 mV in 0.5 M H2SO4 and 1.0 M KOH solutions, respectively, with remarkable durability for 100 h.

Lignin as a quasi-homogenous electron mediator enables efficient photocatalytic H2 evolution in molecular systems.

We report that the biomass-derived lignosulfonate (LS) can function as a quasi-homogenous electron mediator to efficiently promote the electron transfer from the excited erythrosin B (ErB) to the in situ generated Pt cocatalyst under visible light, thus enhancing the photocatalytic H2 evolution activity by over 10 fold as compared to the LS-free system.

In situ self-exsolved ultrasmall Fe2P quantum dots from attapulgite nanofibers as superior cocatalysts for solar hydrogen evolution.

Developing highly active, stable, and cost-efficient cocatalysts for photocatalytic H2 evolution is pivotal in the area of renewable energy conversion. Herein, we present a straightforward, low-temperature phosphidation strategy for in situ exsolving doped Fe ions from natural attapulgite (ATP) nanofibers into a supported Fe2P cocatalyst for the photocatalytic H2 evolution reaction (HER). The resulting Fe2P QDs/ATP features highly dispersed Fe2P QDs with an average size of <2 nm and a strong interfacial interaction between self-exsolved Fe2P QDs and the ATP substrate, thus providing ample and stable active sites for the photocatalytic HER. When employed as a cocatalyst, Fe2P QDs/ATP exhibits superior catalytic activity and notable stability in a molecular system with low-cost xanthene dyes as the photosensitizer under visible light irradiation. More importantly, Fe2P QDs/ATP can also efficiently and stably catalyze the photocatalytic HER when simply combined with various semiconductor photocatalysts (g-C3N4, TiO2, and CdS). This strategy of exsolving transition metal ions from substrates is an effective yet simple approach for the development of highly active supported HER cocatalysts for renewable and clean energy conversion.

Boosting CO2 electroreduction on a Zn electrode via concurrent surface reconstruction and interfacial surfactant modification.

Herein, we report an effective strategy for improving the electrocatalytic CO2 reduction reaction (CO2RR) performance of a Zn foil electrode via concurrent surface reconstruction and interfacial surfactant modification. The oxide-derived and CTAB-modified Zn electrode (OD-Zn-CTAB) prepared by electrochemically reducing the air-annealed Zn foil electrode in the presence of CTAB exhibits high electrocatalytic activity and selectivity for CO production with a CO partial current density (jCO) of 8.2 mA cm-2 and a CO faradaic efficiency (FECO) of 90% at -1.0 V vs. the reversible hydrogen electrode (RHE), greatly outperforming the pristine Zn foil (FECO = 32.0%; jCO = 0.5 mA cm-2) and OD-Zn (FECO = 77.6%; jCO = 5.0 mA cm-2) obtained by electroreduction of annealed Zn. The greatly enhanced CO2RR performance of OD-Zn-CTAB can be attributed to the increased number of active sites originating from the surface reconstruction and the formation of a favorable CTAB-modified electrode/electrolyte (E/E) interface that can efficiently adsorb and activate CO2 while inhibiting the competitive H2 evolution reaction.

Ni2P nanowire arrays grown on Ni foam as an efficient monolithic cocatalyst for visible light dye-sensitized H2 evolution.

Nanostructured H2 evolution cocatalysts are able to promote charge separation and thus enhance the efficiency of the photocatalytic H2 evolution reaction (HER). However, the nanosized cocatalyst particles are easily detached from the surfaces of semiconductors or severely aggregated in reaction systems, which not only greatly reduces the photocatalytic HER efficiency during long-term use but also greatly increases the difficulty of recovery. Moreover, powdery cocatalysts have poor compatibility with the scale-up photoelectrochemical devices. In this paper, a monolithic cocatalyst is developed by controllably growing Ni2P nanowire arrays on Ni foam substrate (Ni2P NWAs/NF) via a direct vapor-phase phosphorization method. The grown Ni2P NWAs with high specific surface areas can not only offer ample active sites for the HER, but also serve as scaffolds for anchoring dye molecules to maximize the light utilization efficiency, which endows the Ni2P NWAs/NF monolithic cocatalyst with excellent HER activity. When sensitized with Erythrosin B (ErB) in triethanolamine (TEOA) solution, the turnover number (TON) of H2 evolution based on ErB reaches 9.7 in 5 h under visible light. Notably, the good structural integrity and inherent magnetism enable the Ni2P NWAs/NF to be easily separated from the reaction solution and excellent catalytic H2 evolution stability over a 45 h cycling reaction. This work presents a new strategy of fabricating monolithic cocatalysts with controllable microstructure and functionalities as well as high activity, durability, and device-compatibility for large-scale solar energy conversion applications.

Ni single atoms supported on hierarchically porous carbonized wood with highly active Ni-N4 sites as a self-supported electrode for superior CO2 electroreduction.

Powdery N-doped carbon-supported single-atom catalysts (SACs) can be prepared on a large scale and are highly selective in converting CO2 to CO, but their practical application is restricted by their powdery texture. Herein, we report Ni single atoms supported on hierarchically porous N-doped carbonized wood (Ni SAs-NCW) as a self-supported electrode for efficient and durable CO2 electroreduction. The porous NCW matrix possesses an abundance of open aligned microchannels that allow unimpeded CO2 diffusion and electrolyte transportation while the uniformly dispersed Ni SAs in the NCW matrix in the Ni-N4 configuration afford ample highly active sites for CO2 electroreduction. This Ni SAs-NCW electrode exhibits a high CO2-to-CO faradaic efficiency (FECO) of 92.1% and a CO partial current density (jCO) of 11.4 mA cm-2 at -0.46 V versus the reversible hydrogen electrode (RHE) and maintains a stable FECO and jCO over a period of 9 h of electrolysis. This work provides an effective strategy to develop efficient SACs with potential to be integrated into flow cell systems for large-scale CO2 reduction.

Carbonized wood membrane decorated with AuPd alloy nanoparticles as an efficient self-supported electrode for electrocatalytic CO2 reduction.

Efficient electrocatalytic reduction of CO2 to value-added chemicals and fuels is a promising technology for mitigating energy shortage and pollution issues yet highly relay on the development of high-performance electrocatalysts. Herein, we develop an effective strategy to fabricate carbonized wood membrane (CW) decorated with AuPd alloy nanoparticles with tunable composition (termed as AuPd@CW) as self-supported electrodes for efficient electrocatalytic CO2 reduction. The uniformly distributed AuPd nanoparticles on wood matrix are first achieved through the in-situ reduction of metal cations by the lignin content in wood. Subsequently, two-step carbonization was employed to promote the alloying of AuPd nanoparticles and the formation of CW. The AuPd@CW membrane electrode features an integrated macroscopic structure with numerous open and aligned channels for rapid electron transfer and mass diffusion and well-dispersed AuPd alloy nanoparticles as active sites for the CO2 reduction. The optimal Au95Pd5@CW electrode affords a high selectivity for CO2 electroreduction with a maximum CO faradaic efficiency (FECO) of 82% at an overpotential of 0.49 V, much higher than those obtained on Au@CW and Pd@CW electrodes. The CO current density and FECO remain relatively stable during a 12 h electrolysis reaction. In addition, density functional theory (DFT) calculations reveal that alloying Au with Pd enables a balance between the formation of intermediate COOH* and the desorption of CO on the surface of AuPd nanoparticles, thus enhancing the selectivity of CO production. This work offers an effective strategy for the fabrication of bimetallic alloys supported on wood-based carbon membrane as a practical electrode for electrochemical energy conversion.

MAPbI3 microcrystals integrated with Ti3C2Tx MXene nanosheets for efficient visible-light photocatalytic H2 evolution.

Integrating Ti3C2Tx MXene nanosheets (Ti3C2Tx NSs) as an efficient cocatalyst with MAPbI3 microcrystals results in superior MAPbI3-Ti3C2Tx NS composite photocatalysts for H2 evolution from MAPbI3-saturated HI aqueous solution using visible light. The best MAPbI3 (100 mg)-Ti3C2Tx NS (10 mg) composite exhibits a H2 evolution rate of 63.6 µmol h-1, which is 43 times higher than that of pristine MAPbI3, and a stable H2 evolution activity over a 120 h repeating reaction.

An all-inorganic quasi-homogenous polyoxometalate/[Mo3S13]2- system for efficient and stable photocatalytic H2 evolution.

An all-inorganic quasi-homogenous photocatalytic H2 evolution system has been developed employing Keggin-type polyoxometalate H4SiW12O40 (SiW12) as the photosensitizer and [Mo3S13]2- clusters as the catalyst. This SiW12/[Mo3S13]2- system achieves a high turnover number (TON) of 922 based on the [Mo3S13]2- catalyst in 5 h of reaction and excellent H2 evolution stability for 40 h with a high turnover number of 6876.

Conductive polyaniline-mediated efficient electron transfer in Z-scheme photocatalysts for enhanced overall water splitting.

Here, we demonstrate that conductive polyaniline (PANI) can function as a solid redox mediator to efficiently shuttle photogenerated electrons from BiVO4 to Ru/SrTiO3:Rh, thus greatly promoting the separation of electrons and holes and nearly quadrupling the overall water splitting activity under visible light irradiation (λ ≥ 420 nm).

Immobilizing cobalt phthalocyanine into a porous carbonized wood membrane as a self-supported heterogenous electrode for selective and stable CO2 electroreduction in water.

Immobilizing a cobalt phthalocyanine (CoPc) molecular electrocatalyst into a porous carbonized wood membrane (CoPc/CWM) results in a self-supported heterogenous electrode. The CoPc/CWM electrode with an ultralow CoPc loading of 8.2 × 10-6 mol cm-2 exhibits a faradaic efficiency (FE) over 90% for CO production at a wide potential range from -0.59 to -0.78 V versus reversible hydrogen electrode (RHE) and excellent long-term durability during a 12 h electrolysis reaction.

In situ embedding of Mo2C/MoO3-x nanoparticles within a carbonized wood membrane as a self-supported pH-compatible cathode for efficient electrocatalytic H2 evolution.

A rational design of active, stable, and pH-compatible electrocatalysts is crucial to produce high-purity H2via an electrocatalytic water splitting reaction. Herein, we report a carbonized wood membrane (CWM) embedded with Mo2C/MoO3-x nanoparticles (denoted as MCWM) as an efficient and stable self-supported H2 evolution cathode in both acidic and alkaline solutions. The CWM features a high surface area with numerous aligned and open channels and abundant porosity, greatly facilitating electrolyte transport and gas release. The in situ embedded Mo2C/MoO3-x nanoparticles are uniformly dispersed throughout the entire framework of the CWM, providing abundant active sites. These structural synergies endow the as-fabricated MCWM electrodes with excellent electrocatalytic H2 evolution activity, and the optimal MCWM electrode requires overpotentials of 187 and 275 mV to achieve a current density of 10 mA cm-2 in 0.5 M H2SO4 and 1.0 M KOH, respectively. Moreover, the MCWM electrode exhibits superior H2 evolution stability at a high current density of 80 mA cm-2 in both solutions with nearly 100% faradaic efficiencies. This work provides a promising nature-inspired strategy for the development of self-supported and pH-compatible electrodes for large-scale electrocatalytic H2 evolution reactions.

Efficient CO2 electroreduction to CO at low overpotentials using a surface-reconstructed and N-coordinated Zn electrocatalyst.

In this work, an effective vapor ammonization-electroreduction strategy is developed to fabricate a surface-reconstructed and N-coordinated Zn electrocatalyst (Zn-N), which exhibits high electrocatalytic activity and stability for CO2 reduction to CO with a faradaic efficiency (FE) of 85.6% and a CO partial current density of 11.2 mA cm-2 at -0.91 V vs. reversible hydrogen electrode (RHE), greatly outperforming Zn foil and surface-reconstructed Zn (Zn-H). Moreover, Zn-N also maintains good selectivity for CO production during the long-term CO2 electrolysis.

A noble-metal-free MoS2 nanosheet-coupled MAPbI3 photocatalyst for efficient and stable visible-light-driven hydrogen evolution.

We report that MoS2 nanosheets (MoS2 NSs) as a cocatalyst in situ coupled with MAPbI3 lead to a highly efficient composite photocatalyst for visible-light-driven photocatalytic H2 evolution. The most efficient MAPbI3/MoS2 NSs composite exhibits a high H2 evolution rate (206.1 µmol h-1) in MAPbI3-saturated HI solution, which is 121 times higher than that of pristine MAPbI3 (1.7 µmol h-1) and greatly superior to that of MAPbI3/Pt/C (68.5 µmol h-1), and the composite is very stable for H2 evolution in a 156 h reaction.

Confining Mo-activated CoSx active sites within MCM-41 for highly efficient dye-sensitized photocatalytic H2 evolution.

Although transition-metal-based sulfides have been identified as efficient catalysts to replace expensive noble metal catalysts for photocatalytic H2 evolution reaction (HER), their activities are still unsatisfied and could be further improved by controlling their microstructures and electronic structures. Herein, we present an effective strategy to confine highly active Mo-activated CoSx (Mo-CoSx) active sites within MCM-41 frameworks by sulfurization of Co-doped MCM-41 during the in situ photoreduction of [MoS4]2- in Erythrosin B-triethanolamine (ErB-TEOA) system. It is found that Co-MCM-41 offers not only abundant coordinatively unsaturated Co sites to be activated by Mo and S but also large surface area to effectively disperse the in situ generated amorphous Mo-CoSx active sites. Under 520 nm irradiation, the most efficient Mo-CoSx/MCM-41-100 (Si/Co = 100) catalyst exhibits ~7, 3, and 4 times higher H2 evolution activity than free MoSx, free Mo-CoSx, and CoSx/MCM-41-100, respectively, and an apparent quantum yield (AQY) of 12.3% for H2 evolution. Furthermore, when Mo-CoSx/MCM-41-100 was sensitized with a more stable fluorescein (FL) dye, the photocatalytic system shows a sustainable H2 evolution activity in a 20 h reaction, showing the good stability of Mo-CoSx/MCM-41-100 catalyst. This work provides a new insight into the design and development of highly active hybrid H2 evolution catalysts based on transition metals for highly efficient and large-scale solar energy conversion to clean H2 energy.

Ti3C2Tx MXene nanosheet-confined Pt nanoparticles efficiently catalyze dye-sensitized photocatalytic hydrogen evolution reaction.

Herein, we report that in situ confined growth of Pt nanoparticles (Pt NPs) on Ti3C2Tx MXene nanosheets (Ti3C2Tx NSs) affords a highly active Ti3C2Tx NSs/Pt NPs hybrid catalyst in a dye-sensitized system under visible light irradiation, which demonstrates ∼30 times higher H2 evolution activity than in situ formed free Pt NPs and acheives a high apparent quantum yeild (AQY) of 5.81% at 520 nm.