Monoxide Poisoning Research Articles

The influence of phosphorus and CO poisoning on Pd/SSZ-13 with different Al distributions as passive NOx adsorbers

Phosphorus and CO are typical poisonous substances under realistic working conditions for Pd/SSZ-13 passive NOx Adsorbers (PNA). In this research, the Pd/SSZ-13 with different Al distributions were subject to phosphorus and CO poisoning. The characterization results indicated the resistance to both P and CO increased with the amount of paired Al on SSZ-13 support. Paired Al facilitated the formation of Pd2+Z2 which was more stable against [Pd(OH)]+ under P poisoning. The Pd2+ preferred to transform to Pd+ after poisoning while the [Pd(OH)]+ was more likely turned to agglomerated Pd. The Al-Pd-Al structure also mitigated dealumination during P poisoning. On the other hand, paired Al promoted the ion-exchange of Pd on the SSZ-13 support and led to a more homogeneous Pd distribution. This effectively alleviated the Ostwald ripening and particle migration thus preserving the performance of the catalyst under CO atmosphere. This study provided a new perspective for designing PNA materials with high resistance.

Designing highly active and CO2 tolerant heterostructure electrode materials by a facile A-site deficiency strategy in Pr1-xBaCo2O5+δ double perovskite

Solid oxide fuel cells (SOFCs) have received continuous attention as an energy conversion device, and the development of highly electrochemically active materials is important. In this work, highly active and CO2 tolerant BaBixCo1-xO3@PrBaCo2O5+δ heterostructure electrode materials were fabricated by a facile A-site deficiency in Pr1-xBaCo2O5+δ double perovskite. A-site excess-deficient Pr0.8BaCo2O5+δ (PBC80) double-perovskite oxide were prepared and designed to induce the self-assembly dissolution to form BaCoO3-δ (BCO) heterostructure through cationic high-concentration deficiency. However, the surface-dissolved alkaline earth metal (Ba2+) readily forms carbonates with CO2, which severely limits the cathode catalytic activity and long-term stability. Thus, bismuth ion-modified PBC80 (BBCO@PBCO) was prepared to further tailor the material properties, which provides more active sites for oxygen reduction reaction (ORR) by strengthening the synergistic interaction between the heterogeneous interfaces. More importantly, BBCO@PBCO exhibits the most stable Area specific resistance (ASR) under CO2 atmosphere, indicating the incorporation of acidic Bi ions effectively mitigated the adsorption and reaction between the material and the acidic gas CO2. These results indicate that the heterostructure induced by A-site deficiency promotes the ORR activity of PrBaCo2O5+δ cathode, while further modification of Bi ions enhances both the electrochemical activity and the stability of the materials, delivering superior resistance to CO2 poisoning.

Investigating the Combined Toxicity of Cu(II) and Carbon Monoxide (CO); Cellular CO Delivery Using a Cu(II) Flavonolato Complex.

Carbon monoxide (CO) delivery molecules are of significant current interest as potential therapeutics, including for anticancer applications. A recent approach toward generating new types of materials-based anticancer agents involves combining the Fenton reactivity of a redox active metal ion with CO delivery. However, small molecule examples of these types of entities have not been systematically studied to evaluate the combined effect on cellular toxicity. Herein we describe a Cu(II) flavonolato complex which produces anticancer effects through a combination of copper-mediated reactive oxygen species (ROS) generation and light-induced flavonol CO release. Confocal microscopy studies provide evidence of enhanced flavonol uptake in the copper flavonolato system relative to the free flavonol, which leads to an increased amount of CO delivery within cells. Importantly, this work demonstrates that a metal flavonolato species can be used to produce enhanced toxicity effects resulting from both metal ion-induced Fenton reactivity and increased cellular uptake of a flavonol CO donor.

Poisoning Mechanism of the CO and H2S Mixture on the Anode of Polymer Electrolyte Membrane Fuel Cell

AbstractDespite the coexistence of CO and H2S in reformed hydrogen, studies on the interaction between impurities are lacking. In this study, the co‐poisoning effect of CO and H2S on a polymer electrolyte membrane fuel cell (PEMFC) is systematically investigated using a hydrogen reference electrode inserted into a membrane electrode assembly (MEA). Notably, when CO and H2S are present simultaneously, the poisoning rate is accelerated and is higher than the simple sum of the poisoning by the individual gases, suggesting a complex synergic effect between the two gases. This phenomenon can be attributed to the potential‐dependent behavior of H2S poisoning, whereas CO poisoning remains independent of the potential but depends on the total poisoning time. Therefore, the potential of the anode rises over time due to the time‐dependent CO poisoning, which accelerates the potential‐dependent H2S poisoning. As a result, the cell voltage decreases more rapidly in the CO and H2S mixture.

Heterointerface engineering of rhombic Rh nanosheets confined on MXene for efficient methanol oxidation

Although metallic rhodium (Rh) is regarded as a promising platinum-alternative anode catalyst of direct methanol fuel cell (DMFC), the conventional “particle-to-face” contact model between Rh and matrix largely limits the overall electrocatalytic performance due to their insufficient cooperative effects. Herein, we report a controllable and robust heterointerface engineering strategy for the bottom-up fabrication of rhombic Rh nanosheets in situ confined on Ti3C2Tx MXene nanolamellas (Rh NS/MXene) via a convenient stereoassembly process. This unique design concept gives the resulting 2D/2D Rh NS/MXene heterostructure intriguing textural features, including large accessible surface areas, strong “face-to-face” interfacial interactions, homogeneous Rh nanosheet distribution, ameliorative electronic structure, and high electronic conductivity. As a consequence, the as-prepared Rh NS/MXene nanoarchitectures exhibit exceptional electrocatalytic methanol oxidation properties in terms of a large electrochemically active surface area of 126.2 m2 g−1Rh, a high mass activity of 1056.9 mA mg−1Rh, and a long service life, which significantly outperform those of conventional particle-shaped Rh catalysts supported by carbon black, carbon nanotubes, reduced graphene oxide, and MXene matrixes as well as the commercial Pt nanoparticle/carbon black and Pd nanoparticle/carbon black catalysts with the same noble metal loading amount. Density functional theory calculations further demonstrate that the direct electronic interaction at the well-contacted 2D/2D heterointerfaces effectively enhances the adsorption energy of Rh nanosheets and induces a left shift of the d-band center, thereby making the Rh NS/MXene configuration suffer less from CO poisoning. This work highlights the importance of rational heterointerface design in the construction of advanced noble metal/MXene electrocatalysts, which may provide new avenues for developing the next-generation DMFC devices.

Construction of MOF-5 derived ZnO composites porous carbon supported Pd nanoparticles as highly stable catalyst for methanol and ethanol oxidation

The preparation of highly active and stable Pd-based catalysts for direct alcohol fuel cells (DAFC) is hampered by inefficient utilization of the active sites, susceptibility to CO poisoning, poor stability, and relatively slow reaction kinetics. Herein, the stability and anti-toxicity of the catalysts (Pd/ZnO/MDC) are tuned by loading Pd nanoparticles on the carbon-coated ZnO support, achieving efficient electrocatalysis for methanol and ethanol oxidation reaction (MOR and EOR). TEM result shows the ZnO is covered by the carbon layer formed outside of MOF-5 derived porous carbon, which can prevent it from dissolving under harsh conditions. The mass activities of the well-tuned catalyst Pd/ZnO/MDC(800) for MOR and EOR are 931.83 mA/mg and 1838.30 mA/mg, respectively. It is due to the improved electron transport efficiency between the Pd and ZnO, and the enhanced stability by carbon layer outside the ZnO. It is also found that the onset potential and the peak potential of Pd/ZnO/MDC(800) (−0.813 V, −0.228 V) in CO stripping experiment in MOR are more negative than Pd/MDC(800) (−0.261 V, −0.215 V). This result indicates that the existence of ZnO helps to provide surface hydroxyl group, which promotes the oxidation of the intermediates. This work indicates provides a feasible idea for DAFC catalyst design and construction.

Pediatric Polytrauma Fire Victim Simulation.

Pediatric trauma has long been one of the primary contributors to pediatric mortality. There are multiple cases in the literature involving cyanide (CN) toxicity, carbon monoxide (CO) toxicity, and smoke inhalation with thermal injury, but none in combination with mechanical trauma. In this 45-minute simulation case, emergency medicine residents and fellows were asked to manage a pediatric patient with multiple life-threatening traumatic and metabolic concerns after being extracted from a van accident with a resulting fire. Providers were expected to identify and manage the patient's airway, burns, hemoperitoneum, and CO and CN toxicities. Forty learners participated in this simulation, the majority of whom had little prior clinical experience managing the concepts highlighted in it. All agreed or strongly agreed that the case was relevant to their work. After participation, learner confidence in the ability to manage each of the learning objectives was high. One hundred percent of learners felt confident or very confident in managing CO toxicity and completing primary and secondary surveys, while 97% were similarly confident in identifying smoke inhalation injury, preparing for a difficult airway, and managing CN toxicity. This case was a well-received teaching tool for the management of pediatric trauma and metabolic derangements related to fire injuries. While this specific case represents a rare clinical experience, it is within the scope of expected knowledge for emergency medicine providers and offers the opportunity to practice managing multisystem trauma.

Demographics and clinical characteristics of carbon monoxide poisoning for patients attending in the emergency department at a tertiary hospital in Riyadh, Saudi Arabia

BackgroundCarbon Monoxide (CO) is one of the most common environmental causes of acute intoxication globally. It can lead to the development of Delayed Neuropsychiatric Sequelae (DNS) which may develop in 2-40 days after remission of acute CO poisoning. DNS is defined by recurrent-transient neurological, cognitive, or psychological manifestations. This study was intended to describe the demographics and characteristics of CO poisoning patients attending at the Emergency Department (ED) and assess the association between CO intoxication and the development of DNS in a tertiary hospital, Riyadh, Saudi Arabia.MethodsA retrospective descriptive cross-sectional study was conducted in subjects who were diagnosed with CO poisoning and attended to the ED at King Abdulaziz Medical City (KAMC) and King Abdullah Specialist Children’s Hospital (KASCH) in Riyadh during the period from January 2016 to December 2021. Patient demographics, vitals, diagnostic tests, and oxygen therapy at initial presentation were documented. Patient medical records were reviewed at 2-40 days following CO poisoning for development of DNS. Ethical approval was obtained from King Abdullah International Medical Research Center (KAIMRC).ResultsA total of 85 patients were diagnosed with CO poisoning and met the study inclusion criteria. Of those, 76% were adults with an average age of 32.36 (SD ± 15.20) and 51% were male adults. Five (6%) of the 85 patients developed DNS. Common symptoms included dizziness, nausea, and decreased visual acuity in 40% of the cases. The development of DNS manifestations was most likely (80%) to occur at 2 to 10 days after the initial incident. Inferential statistics showed that BMI (p-value = 0.021) and age group (p-value = 0.029) were significantly associated with COHb level, which was not the case for gender and the presence of clinical manifestation. Furthermore, Gender was significantly associated with the development of DNS (20% male vs. 80% female, p = 0.050).ConclusionsThe findings of this study are consistent with previous published studies showing low proportions of patients who were exposed to CO poisoning at risk of developing DNS. Further larger-scale multicenter studies are needed to assess the factors associated with the development of DNS for patients with CO poisoning.

Research on preparation of high activity and durable carbon-supported platinum catalyst for methanol electro-oxidation by a facile continuous microwave pipeline method

In methanol oxidation reaction (MOR), it is crucial for the catalyst that Pt particles uniformly cover the surface of the carrier and the Pt surface active sites can effectively remove the binding with CO. This article develops a simple and effective continuous microwave technology. Carbon loaded nano platinum was synthesized by rapidly and uniformly heating a ethylene glycol mixture containing carbon black (CB) H2PtCl6 using microwave radiation, with a Pt content of 49.5%. The experimental results indicate that platinum particles are uniformly loaded onto the carbon surface, with uniform shape and size, and an average particle size of 3.02 nm. And the Pt/C catalyst prepared by continuous microwave technology showed enhanced electrocatalytic activity (peak current density of 76.95 mA/cm2) in MOR after heating at appropriate temperature in N2 atmosphere, which exceeded the commercial catalyst TKK (47.07 mA/cm2) by 63.6%. And the catalyst's resistance to CO toxicity and durability; Higher than commercial Pt/C catalysts. Compared with traditional methods, continuous microwave technology exhibits higher energy utilization efficiency and faster reaction speed in the catalyst preparation process. This technology also has the ability to achieve continuous preparation, which is one of the effective technological approaches to achieve large-scale catalysts production.

Facile Deficiency Engineering in a Cobalt-Free Perovskite Air Electrode to Achieve Enhanced Performance for Protonic Ceramic Fuel Cells.

As a crucial component responsible for the oxygen reduction reaction (ORR), cobalt-rich perovskite-type cathode materials have been extensively investigated in protonic ceramic fuel cell (PCFC). However, their widespread application at a commercial scale is considerably hindered by the high cost and inadequate stability. In response to these weaknesses, the study presents a novel cobalt-free perovskite oxide, Ba0.95La0.05(Fe0.8Zn0.2)0.95O3-δ (BLFZ0.95), with the triple-conducting (H+|O2-|e-) property as an active and robust air electrode for PCFC. The B-site deficiency state contributes significantly to the optimization of crystal and electronic structure, as well as the increase in oxygen vacancy concentration, thus in turn favoring the catalytic capacity. As a result, the as-obtained BLFZ0.95 electrode demonstrates exceptional electrochemical performance at 700 °C, representing extremely low area-specific resistance of 0.04 Ω cm2 in humid air (3 vol.% H2O), extraordinarily high peak power density of 1114mW cm-2, and improved resistance against CO2 poisoning. Furthermore, the outstanding long-term durability is achieved without visible deterioration in both symmetrical and single cell modes. This study presents a simple but crucial case for rational design of cobalt-free perovskite cathode materials with appreciable performance via B-site deficiency regulation.

Failure Mechanism and Stability Enhancement Strategies for Self‐Supported Electrodes

AbstractIn the face of global climate change and the need for energy diversification, electrocatalytic technology emerges as an eco‐friendly solution. However, persistent electrode failures hinder long‐term stability. This review comprehensively outlines the primary causes leading to the failure of self‐supported electrodes, encompassing substrate passivation, substrate/catalyst dissolution, CO poisoning, catalyst migration and agglomeration, as well as cathodic etching. Proposed strategies center on material design, emphasizing anchoring, lattice matching, substrate stability, and morphological control. Advanced characterization techniques and in situ technologies offer promising ways. The integrated deployment of these strategies will provide crucial guidance and support for the sustainable advancement of electrocatalytic technology.

Facile Synthesis of High-Entropy Alloy Nanowires for Electrocatalytic Alcohol Oxidation.

Considering the structural and compositional advantages of high-entropy alloy (HEA) as high-efficient electrocatalysts, we here present a facile method to prepare high-entropy alloy nanowires with seven elements in an aqueous solution. The as-synthesized PdPtCuAgAuPbCo nanowires possess dispersed one-dimensional morphology and exhibit enhanced electrocatalytic performance with the mass activity of 9.9 A mgPd+Pt -1 toward ethanol electrooxidation. The HEA nanowires also perform superior stability, resistance to CO poisoning, and good electrocatalytic activities toward other alcohols (e. g., ethylene glycol and methanol) oxidation. The synthesis strategy is easy to operate with low cost and has wide application prospects for preparing desired electrocatalysts for fuel cells.

Biomimetic Frustrated Lewis Pair Catalysts for Hydrogenation of CO to Methanol at Low Temperatures.

The industrial production of methanol through CO hydrogenation using the Cu/ZnO/Al2O3 catalyst requires harsh conditions, and the development of new catalysts with low operating temperatures is highly desirable. In this study, organic biomimetic FLP catalysts with good tolerance to CO poison are theoretically designed. The base-free catalytic reaction contains the 1,1-addition of CO into a formic acid intermediate and the hydrogenation of the formic acid intermediate into methanol. Low-energy spans (25.6, 22.1, and 20.6 kcal/mol) are achieved, indicating that CO can be hydrogenated into methanol at low temperatures. The new extended aromatization-dearomatization effect involving multiple rings is proposed to effectively facilitate the rate-determining CO 1,1-addition step, and a new CO activation model is proposed for organic catalysts.

Mechanisms of Action of Toxins Released by Clostridium perfringens

Clostridium perfringens, a rod-shaped anaerobe, is a Gram-positive bacterium that causes foodborne diseases. Its generation time is less than ten minutes and it can divide at 45°C. This aerotolerant bacterium has some toxigenic types (A, B, C, D, and E) that can cause diseases in human beings. Two of its newly discovered toxin types are F and G. Histotoxic, neurological, and intestinal illnesses in both people and animals are instigated by C. perfringens due to its wide range of protein toxins. Alpha or CPA, beta or CPB, epsilon or ETX, iota or ITX, and enterotoxin or CPE are the primary toxins that contribute toward diseases. CPA is the primary pathogenicity factor in gas poisoning in human beings, despite its limited and debatable involvement in animal illnesses. Necrotizing intestinal inflammation and enterotoxaemia in infants of various vertebrate species, particularly humans, are caused by CPB. Some other types cause illnesses in livestock. Necrotic and apoptotic traits are present in the molecular pathways of cell damage linked to C. perfringens toxins.

Low-Pt anodes with gradient molybdenum isomorphism for high performance and anti-CO poisoning PEMFCs

The development of low Pt-loading hydrogen oxidation reaction electrocatalysts with high catalytic activity, durability, and resistance to CO poisoning is essential for the commercialization of proton exchange membrane fuel cells. Herein, two hybrid catalysts coupled with single atoms are prepared. Electrochemical tests show that PtMo1/KB (Ketjen Black) (1.85 wt% Pt) exhibits extraordinary HOR activity and durability, with the mass activity in electrochemical cells and even PEMFCs are 8.36 and 2.71 times higher than that of commercial Pt/C, respectively. In addition, PtMo10/KB with novel configuration performed super high CO resistance (1000 ppm) in both three electrode and PEMFC measurement with an ultra-low Pt loading of 1.56 wt%, demonstrating the high application value in the next generation highly efficient PEMFC. DFT calculations also show that the adsorption energy of the intermediates H* and CO is optimized by tuning the d-band center of Pt, thus enhancing the HOR activity and CO tolerance of the catalyst. Meanwhile, in situ CO-adsorption surface-enhanced infrared adsorption spectroscopy also confirms that the weakening of the Pt-CO bond strength and the adsorption energy of CO contributes to the improvement of CO tolerance in PtMo10/KB.

Deposited PtGe Clusters as Active and Durable Catalysts for CO Oxidation**

AbstractControl of CO emissions raises serious environmental concerns in the current chemical industry, as well as in nascent technologies based on hydrogen such as electrolyzers and fuel cells. As for now, Pt remains one of the state‐of‐the‐art catalysts for the CO oxidation reaction, but unfortunately, it suffers from CO self‐poisoning. Recently, Pt−Ge alloys were proposed to be an excellent alternative to reduce CO poisoning. This work investigates the impact of Ge content on the CO oxidation kinetics of Pt4Gen subnanoclusters supported on MgO. A Ge concentration dependence of the reaction kinetics is found due to a strong synergy between Pt and Ge. Pt−Ge nanoalloys act as a bifunctional catalyst by displaying dual adsorption sites; i. e., CO is adsorbed on Pt whereas oxygen binds to Ge, forming an alternative oxygen source GeOx. Besides, Ge alloying modifies the electronic structure of Pt (ligand effects) and reduces the affinity to CO. In this way, the competition between CO and O2 adsorption and the overbinding of CO is alleviated, achieving a CO poisoning‐free kinetic regime. Our calculations suggest that Pt4Ge3 is the optimal catalyst, evidencing that alloying composition is a parameter of extreme importance in nanocatalyst design. The work relies on global optimization search techniques to determine the accessibility of multiple structures at different conditions, mechanistic studies and microkinetic modeling.

Gas Therapy: Generating, Delivery, and Biomedical Applications.

Oxygen (O2), nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S), and hydrogen (H2) with direct effects, and carbon dioxide (CO2) with complementary effects on the condition of various diseases are known as therapeutic gases. The targeted delivery and in situ generation of these therapeutic gases with controllable release at the site of disease has attracted attention to avoid the risk of gas poisoning and improve their performance in treating various diseases such as cancer therapy, cardiovascular therapy, bone tissue engineering, and wound healing. Stimuli-responsive gas-generating sources and delivery systems based on biomaterials that enable on-demand and controllable release are promising approaches for precise gas therapy. This work highlights current advances in the design and development of new approaches and systems to generate and deliver therapeutic gases at the site of disease with on-demand release behavior. The performance of the delivered gases in various biomedical applications is then discussed.

CO2/Cr-tolerance and oxygen reduction reaction of novel high-entropy perovskite cathode for intermediate temperature solid oxide fuel cell

The development and exploration of cathode oxides with outstanding electrocatalytic activity are critical processes aimed at achieving a decrease in the operation temperature of solid oxide fuel cells (SOFC). Herein, a novel high-entropy oxide, La0.2Pr0.2Nd0.2Sm0.2Gd0.2BaCoFeO5+δ (HEP), which incorporates five lanthanide species (La, Pr, Nd, Sm, and Gd) in the A-site of perovskite, has been specifically developed and assessed as selected cathode for intermediate-temperature SOFC. Investigations of phase structure, chemical compatibility, oxygen transport characteristics, oxygen reaction kinetic, thermal expansion, surface chemical state, conductivity, as well as CO2/Cr-durability are thoroughly performed to assess the basic physicochemical properties of the HEP cathodes. The HEP cathode possesses good operational stability, moderate thermal expansion behavior, fast oxygen transport dynamics, and superior chemical compatibility with the electrolyte. At 700 °C, the polarization resistance low to 0.072 Ω cm2 and output power density high to 332.2 mW cm−2 were obtained for the symmetrical and electrolyte-supported single cells. Furthermore, a stable current density is obtained for the single cell operating at 600 °C and 0.5 V for 100 h. Analysis of electrochemical impedance spectra (EIS) and distribution of relaxation time (DRT) data at different oxygen partial pressures reveal that the charge-transfer and oxygen ions ionization processes at intermediate frequencies present a significant limiting step in the rate of the oxygen reduction reaction. However, under realistic utilization conditions, cathodes of cells often endure irreversible performance degradation owing to the Cr deposition from interconnects or CO2 poisoning in air. Hence, the behavior of Cr and CO2 poisoning is also systematically investigated in symmetrical cell measurements; the results confirm that the HEP cathode displays good resistance to Cr and CO2 poisoning. Overall, our findings indicate that the HEP material is regarded as a favored ceramic cathode for SOFC.

Spatio-temporal analysis of deaths from carbon monoxide poisoning in Iran between 2011 and 2018: An ecological study.

Mortality caused by carbon monoxide every year threatens the lives of Iranian people, whose spatial and temporal distribution is not known for formulating prevention policies and interventions. This study was conducted to determine the trend of mortality rate changes due to carbon monoxide CO poisoning by Spatio-temporal analysis in Iran from 2011 to 2018. An ecological study was conducted based on data from the reports at the National Center for Statistics of Iran for 8 years from 21 March 2011 to 21 March 2018. The number of deaths due to CO poisoning and the annual mortality rates of CO poisoning per 100,000 populations were calculated. To determine the geographical and temporal distribution of death caused by carbon monoxide, spatiotemporal statistical analysis was used. A total of 6078 deaths were reported due to CO poisoning 4497 deaths were male (74%) and 1596 were female (26%) from 2011 to 2018. Both sexes'mortality rate due to CO poisoning was 1.26 from 2011 to 0.91 in 2018. According to the results, the overall male-to-female ratio was 2.8. The mortality rate due to CO Poisoning had a decreasing trend. However, this trend did not have a linear trend (p = 0.37). The highest mortality due to CO poisoning was seen in the northern and western provinces of Iran. Our results showed that the mortality rate due to CO poisoning had a decreasing trend during the understudied period. Also, most of the deaths due to CO poisoning occurred in the northern and western provinces of Iran. So, designing prevention programs as well as increasing people's awareness in these regions is recommended.

Recent advances in nanoscale engineering of Pd-based electrocatalysts for selective CO2 electroreduction to formic acid/formate

Electrochemical conversion of carbon dioxide (CO2) into high-value chemicals and fuels driven by electricity derived from renewable energy has been recognized as a promising strategy to achieve carbon neutrality and create sustainable energy. Particularly from the viewpoint of the product values and the economic viability, selective CO2 reduction to formic acid/formate has shown great promise. Palladium (Pd) has been demonstrated as the only metal that can produce formic acid/formate perfectly near the equilibrium potential; yet, it still suffers from CO poisoning, poor stability and competitive CO pathway at high overpotentials. Herein, recent progress of Pd-based electrocatalysts for selective CO2 electroreduction and their mechanistic understanding are reviewed. First, the fundamentals of electrochemical CO2 reduction and the reaction pathway of formic acid/formate on Pd are presented. Then, recent advances in the rational design and nanoscale engineering strategies of Pd-based electrocatalysts for further improving CO2 reduction activity and selectivity to formic acid/formate product, including size control, morphology and shape control, alloying, heteroatom doping, surface-strain engineering, and phase control, are discussed from the perspectives of both experimental and computational aspects. Finally, we discuss the pertinent challenges and describe the future prospects and opportunities in terms of the development of electrocatalysts, electrolyzers and characterization techniques in this research field.